Immune potentiating compositions of cancer cells

ABSTRACT

The present invention relates various compositions having an immunostimulatory molecule and animal cells cultured in the presence of at least one interferon (IFN) of type I or type II for time and conditions sufficient to enhance the antigen presenting function of the cells. Other aspects of the present invention include methods of treatment and/or prophylaxis of a disease or condition using these immunopotentiating compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is the U.S. National Phase under 35 U.S.C. §371 of International Application No. PCT/AU01/00565, filed May 17, 2001, designating the United States and published in English, which claims priority to Australian Application No. PQ 7553, filed May 17, 2000, the disclosure of which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

THIS INVENTION relates generally to immune potentiating compositions. More particularly, the present invention is directed to compositions of matter comprising cells exhibiting enhanced antigen presenting functions. The compositions of the present invention are generally useful in facilitating the stimulation of host immune cell responses, including selective and targeted immune cell responses. The compositions of the present invention are particularly useful in the treatment and/or prophylaxis of cancers and tumours.

Bibliographic details of the publications numerically referred to in this specification are collected at the end of the description.

BACKGROUND OF THE INVENTION

The interferons (IFNs) comprise a group of glycoproteins produced by various cells in response to viral infections, specific antigens or mitogens. Since their discovery (1), the IFNs have been found to play important roles in, for example, antiviral, anti-proliferative, differentiative and immunomodulatory responses (2).

Following binding of IFNs to their receptor, intracellular tyrosine kinases of the JAK family become activated and phosphorylate transcription factor molecules called Stats (Signal transducers and activators of transcription). IFN-gamma signals by activating the formation of a homodimer of Stat 1. IFN-alpha or beta mainly signal by activating the interferon sensitive gene factor 3 (ISGF3), a complex of Stat1 and/or Stat2, as homo or heterodimers that combine to produce trimeric molecules containing a third protein, p48 ISGF3-gamma. After activation, the transcription factor complexes migrate to the nucleus, binding to target DNA sequences thereby affecting the expression of interferon sensitive genes (ISGs). The Stat1 homodimer binds a sequence TTCNNNGAA, known as the GAS site. IFN signalling also activates one other interferon regulator factor, IRF-1. Both factors, IRF-1 and ISGF3 bind via regulatory response elements in the promoter regions of ISGs that comprise direct repeats of the DNA sequence GAAANN, leading to activation of transcription from the IGS (for reviews, see (3, 4)).

The genes encoding IFNs and components of the IFN signalling pathway are proposed to belong to a family of tumour suppressor genes (5). Accordingly, mutations disrupting any steps in the IFN signal transduction pathway would be expected to reduce cellular responsiveness to IFN, abrogating the tumour suppressive function of IFN action and thereby facilitating the onset of cancer.

The effect of IFN in the treatment of advanced malignant melanoma has been demonstrated in several clinical trials. In this regard, IFN-alpha is effective in only a group (˜23%) of skin melanoma patients. An explanation was proposed for this phenomenon based on abnormalities detected in the IFN signalling properties of melanoma cells (6-8). Studies on growth of short-term cultures at low passage number established from advanced stage m metastatic melanomas revealed all patients' samples to be resistant to IFN when compared to IFN-sensitive melanoma cell lines and melanocytes (6). As a result, the majority of patients with advanced metastatic melanomas will fail to respond significantly to IFNs because their tumour cells fail to adequately respond to the direct actions of the IFNs. IFNs act in vivo in two ways to either indirectly stimulate immune effector cells or directly act on the tumour cell targets (9). Studies of tumour cell lines produced in knockout mice which have been made IFN-insensitive (by using either Stat1-deficient or IFN-gamma receptor-deficient mice) have revealed that the direct effects of IFN are important for immune surveillance (10). Cancer cells established in the IFN-gamma insensitive mice, when passaged into syngeneic wild type mice, were no longer rejected by the immune system. Thus, it was concluded that IFN action was mediated in part through its direct effects on the tumour cells, presumably by inducing enhanced tumour cell immunogenicity (10). Thus, loss of responsiveness to IFNs as tumour suppressors is one of the early and important developments in the onset of malignancy as it allows tumours to evade immune surveillance, providing the tumours with a significant survival advantage.

Many studies have reported various defects in the IFN system as being responsible for the different sensitivities to type I IFNs in cell lines established from other tumour types: (i) IFN-alpha/-beta gene deletion in acute leukaemia cell lines (11) and malignant T cells (12); (ii) alteration or down regulation of IFN-alpha receptor gene expression in hairy cell leukaemia (13) and lymphoblastoid cells (14); (iii) interference with the induction of the expression of IFN-stimulated genes in B lymphoid cell lines (15) and Burkitt's lymphoma cells (16); (iv) defects in the activation of transcription factors in Daudi cells (17) and primary leukaemia cells (18). In addition, melanoma cell lines with a wide variation in their responsiveness to the anti-proliferative (19) and antiviral (20) activities of IFNs, ranging from highly sensitive to relatively resistant, have been described.

Initial studies by the present inventors on IFN signalling in melanoma cell lines with different responsiveness to IFN revealed that these cell lines did not show significant differences in the levels of IFN binding to cell surface receptors (21) or in the activation of the IFN receptor associated JAK tyrosine kinases (7). Thus, loss of IFN responsiveness did not appear to be due to abnormalities in the IFN mediated activation of receptor signalling. However, in all IFN-resistant melanoma cells examined, deficiencies were detected at the next level in the IFN activated signalling pathways (6). In this regard, much lower intracellular levels of the trans-activating relay factors essential for transmitting the IFN signal from the membrane to the cell nucleus were detected [for review, see 8]. Hence, changes in gene expression normally induced by IFNs and which are essential if tumours are to be recognized and eliminated by the body's immune system will not occur in the IFN-resistant tumour cells because the signal reaching the nucleus is insufficient.

Cellular responsiveness to IFNs can be increased by prior treatment with IFN (22). This process, called “priming” (6), increases the levels of the cognate transcription factors, including IRF-1 and all three components of ISGF3: Stat1; Stat2; and p48. Regulation of the IRF-1, Stat2 and p48 promoters have been described (for example, see (23) and expression of these genes is regulated by the IFNs. Stat1 protein is involved in activating expression of IRF-1, p48 and Stat2.

Stat1 is at a pivotal point in IFN signalling as it is required for both type I and II IFN receptor signals (3). The regulation of Stat1 activity has become an important biological question for other reasons as well, given other key roles for Stat1 in important cell functions. Thus, IFNs act via Stat1 to regulate cell growth by directly inducing expression of the cell cycle inhibitor, CKI p21 WAF (24, 25). In addition, Stat1 regulates expression of caspases 1, 2 and 3 involved in apoptosis (26).

In work leading up to the present invention, the inventors' analyses of human melanoma cells revealed that Stat1 (6, 7) and IRF-1 were consistently deficient in IFN-resistant melanoma cells. In particular, the evidence pointed to a key role for the transcription factor, Stat1, which was poorly expressed at the mRNA and protein levels in IFN-resistant cells and moreover, responsiveness to IFN was greatly increased by transfecting IFN-resistant melanoma cells to express increased levels of Stat1 (6). Similar results have been shown to occur in breast cancer cell samples as well (27, 28) raising the possibility of a more widespread problem, which highlights the broader significance of Stat1 deficiency to cancers in general. Consistent with this hypothesis, several studies have since reported other cancer types in which Stat1 deficiencies have been commonly noted (29, 30).

The present inventors also found that by treating melanoma cells with high levels of IFN-gamma (gamma-priming), the treated cells express markedly increased levels of Stat1 as well as of p48 and Stat2 (6). Even in type I IFN-resistant melanoma cells, Stat1 levels were increased after gamma-priming. In addition, the cellular responsiveness to treatment with type I IFN was increased after gamma-priming, including significantly greater ISGF3 binding activity detected by electrophoretic gel mobility shift assay (EMSA) and increased induction of ISGs detected by immunochemical methods. Amongst the ISGs whose expression was increased were the IFN inducible surface antigens, class I MHC and ICAM-1 (6), which are important in immune cell recognition of tumour cells.

SUMMARY OF THE INVENTION

The present inventors have surprisingly discovered that a stronger immune response against a cancer can be elicited by vaccination with a composition comprising interferon treated cancer cells in combination with an immunostimulatory molecule that is either present on the surface of the cancer cells or in soluble form. The combination of interferon treatment and immunostimulatory molecule produces a synergistic enhancement in antigen presenting function of the treated cells, which when introduced into a suitable host, elicit a markedly improved stimulation of the immune response against antigens presented by those cells. The above discovery has been reduced to practice in the form of compositions of matter, kits, assays and methods of treatment, as described hereinafter.

Thus, in one aspect of the present invention, there is provided a composition of matter comprising an immunostimulatory molecule and animal cells cultured in the presence of a type II interferon (IFN) in exogenous form and at least one type I IFN in exogenous form for a time and under conditions sufficient to enhance the antigen presenting function of said cells, wherein said animal cells have been washed to remove said IFNs.

In a preferred embodiment, the type II IFN is present in the culture medium at a concentration of about 100 to about 2000 international units/mL.

In another preferred embodiment, the type I IFN is present in the culture medium at a concentration of about 100 to about 2000 international units/mL.

The immunostimulatory molecule can be present on the surface of said cells or in soluble form.

The animal cells are preferably cancer or tumour cells. Suitably, the cancer or tumour cells include, but are not restricted to, melanoma cells and mammary carcinoma cells.

In another aspect of the present invention, there is provided a method for enhancing immunopotentiation of animal cells, comprising:

-   -   culturing animal cells expressing an immunostimulatory membrane         molecule in the presence of a type II interferon (IFN) in         exogenous form and at least one type I IFN in exogenous form for         a time and under conditions sufficient to enhance the antigen         presenting functions of said cells; and     -   washing said cells to remove said IFNs.

Preferably, the method further comprises isolating cells expressing said immunostimulatory membrane molecule from a heterogeneous population of animal cells.

The method may further comprise modifying the animal cells to express said immunostimulatory membrane molecule.

Preferably, the step of modification comprises introducing into said animal cells a polynucleotide from which the immunostimulatory membrane molecule can be expressed.

Suitably, the animal cells are cultured by contacting said cells with a type II IFN for a time and under conditions sufficient to permit cellular responsiveness to at least one type I IFN and then contacting said cultured cells with the at least one type I IFN for a time and under conditions sufficient to enhance the antigen presenting function of said cells.

Preferably, the type II IFN is selected from the group consisting of an IFN-gamma, a biologically active fragment of an IFN-gamma, a variant of an IFN-gamma, a variant of a said biologically active fragment, a derivative of an IFN-gamma, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-gamma.

The at least one type I IFN is preferably selected from the group consisting of an IFN-alpha, an IFN-beta, a biologically active fragment of an IFN-alpha, a biologically active fragment of an IFN-beta, a variant of an IFN-alpha, a variant of an IFN-beta, a variant of a said biologically active fragment, a derivative of an IFN-alpha, a derivative of an IFN-beta, a derivative of a said biologically active fragment, a derivative of a said variant, an analogue of an IFN-alpha and an analogue of an IFN-beta.

Preferably, the method as broadly described above further comprises rendering the animal cells inactive or incapable of proliferation. For example, the animal cells may be irradiated with a suitable amount of radiation such as, for example, gamma-irradiation, as is known in the art, to render the animal cells incapable of proliferating in the intended host.

In yet another aspect, the invention contemplates a method for enhancing immunopotentiation of animal cells, comprising:

-   -   culturing animal cells in the presence of a type II interferon         (IFN) in exogenous form and at least one type I IFN in exogenous         form for a time and under conditions sufficient to enhance the         antigen presenting functions of said cells;     -   washing said cells to remove said IFNs; and     -   combining said cells with an immunostimulatory molecule in         soluble form.

Another aspect of the present invention resides in a composition of matter comprising an immunostimulatory molecule and animal cells cultured in the presence of a type II interferon (IFN) in exogenous form and one or both of a first type I IFN in exogenous form and a second type I IFN in exogenous form for a time and under conditions sufficient to enhance the antigen presenting function of said cells, wherein said animal cells have been washed to remove said IFNs, wherein said type II IFN is selected from the group consisting of an IFN-gamma, a biologically active fragment of an IFN-gamma, a variant of an IFN-gamma, a variant of a said biologically active fragment, a derivative of an IFN-gamma, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-gamma, wherein said first type I IFN is selected from the group consisting of an IFN-beta, a biologically active fragment of an IFN-beta, a variant of an IFN-beta, a variant of a said biologically active fragment, a derivative of an IFN-beta, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-beta, and wherein said second type I IFN is selected from the group consisting of an IFN-alpha, a biologically active fragment of an IFN-alpha, a variant of an IFN-alpha, a variant of a said biologically active fragment, a derivative of an IFN-alpha, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-alpha.

In yet another aspect, the invention features a composition of matter comprising an immunostimulatory molecule and animal cells cultured in the presence of a type II interferon (IFN) in exogenous form and a type I IFN in exogenous form for a time and under conditions sufficient to enhance the antigen presenting function of said cells, wherein said animal cells have been washed to remove said IFNs, wherein said type II IFN is selected from the group consisting of an IFN-gamma, a biologically active fragment of an IFN-gamma, a variant of an IFN-gamma, a variant of a said biologically active fragment, a derivative of an IFN-gamma, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-gamma, and wherein said type I IFN is selected from the group consisting of an IFN-beta, a biologically active fragment of an IFN-beta, a variant of an IFN-beta, a variant of a said biologically active fragment, a derivative of an IFN-beta, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-beta.

In another aspect, the invention extends to a composition of matter comprising an immunostimulatory molecule and animal cells cultured in the presence of a type II interferon (IFN) in exogenous form and a type I IFN in exogenous form for a time and under conditions sufficient to enhance the antigen presenting function of said cells, wherein said animal cells have been washed to remove said IFNs, wherein said type II IFN is selected from the group consisting of an IFN-gamma, a biologically active fragment of an IFN-gamma, a variant of an IFN-gamma, a variant of a said biologically active fragment, a derivative of an IFN-gamma, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-gamma, and wherein said type I IFN is selected from the group consisting of an IFN-alpha, a biologically active fragment of an IFN-alpha, a variant of an IFN-alpha, a variant of a said biologically active fragment, a derivative of an IFN-alpha, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-alpha.

In another aspect, the invention contemplates a method for enhancing or otherwise improving the immunogenicity of an antigen, comprising:

-   -   providing animal cells cultured in the presence of a type III         interferon (U in exogenous form and at least one type I IFN in         exogenous form for a time and under conditions sufficient to         enhance the antigen presenting functions of said cells, wherein         said animal cells have been washed to remove said IFNs; and     -   loading said antigen onto the IFN-treated animal cells.

Suitably, the antigen is of viral, bacterial, fungal, or protozoan origin.

According to another aspect, the invention envisions a composition of matter for eliciting an immune response against a target antigen, comprising animal cells cultured in the presence of a type II interferon (IFN) in exogenous form and at least one type I IFN in exogenous form for a time and under conditions sufficient to enhance the antigen presenting functions of said cells, wherein said animal cells have been washed to remove said IFNs and wherein an antigen corresponding to said target antigen has been loaded onto the IFN-treated animal cells.

In another aspect, the invention resides in a vaccine for stimulating a host's immune system, comprising a composition of matter as broadly described above, said vaccine optionally further comprising one or more pharmaceutically acceptable carriers, adjuvants and/or diluents.

In yet another aspect, the invention provides a method for treatment and/or prophylaxis of a disease or condition, comprising administering to a patient in need of such treatment a therapeutically effective amount of a composition or vaccine as broadly described above.

In one embodiment, said administration comprises administering separately, sequentially or simultaneously to the patient a soluble immunostimulatory molecule and the cultured animal cells.

According to a further aspect, the invention provides a kit comprising a composition of matter including animal cells cultured in the presence of a type II interferon (IFN) in exogenous form and at least one type I IFN in exogenous form for a time and under conditions sufficient to enhance the antigen presenting function of said cells, wherein said animal cells have been washed to remove said IFNs, together with an immunostimulatory molecule.

In a preferred aspect of the invention, there is provided a method for treatment and/or prophylaxis of tumorigenesis, comprising administering to a patient in need of such treatment a therapeutically effective amount of a composition or vaccine as broadly described above.

In a still further aspect, the invention provides a process for assessing the responsiveness of animal cells to treatment with at least one interferon (IFN), comprising detecting in said animal cells the level and/or functional activity of a polypeptide involved in IFN signalling or the level and/or functional activity of a modulatory agent that modulates said polypeptide or the level and/or functional activity of a downstream cellular target of said polypeptide or the level of an expression product of a genetic sequence encoding a member selected from the group consisting of said polypeptide, said modulatory agent and said downstream cellular target.

Preferably, the polypeptide is Stat1.

The invention, in yet another aspect, contemplates the use of a target cell in an assay for detecting cytolytic activity of a cytotoxic T lymphocyte (CTL) for said target cell, wherein said target cell has been cultured in the presence of a type II interferon (IFN) in exogenous form and at least one type I IFN in exogenous form for a time and under conditions sufficient to enhance the antigen presenting function of said target cell, and washed to remove said IFNs.

In one embodiment, said target cell expresses an immunostimulatory membrane molecule. In an alternate embodiment, said target cell is contacted with said CTL in the presence of a soluble immunostimulatory molecule.

Preferably, said CTL is a CD8⁺ CTL.

In still yet another aspect, the invention features a method for detecting cytolytic T lymphocyte (CTL) mediated lysis of a target cell, comprising:

-   -   providing a target cell cultured in the presence of a type II         interferon (IFN) in exogenous form and at least one type I IFN         in exogenous form for a time and under conditions sufficient to         enhance the antigen presenting functions of said target cell,         wherein said target cell has been washed to remove said IFNs;     -   contacting the target cell with a CTL that has cytolytic         activity for said target cell; and     -   detecting CTL-mediated lysis of said target cell.

The invention also encompasses -the use of a member selected from the group consisting of an antigen binding molecule that is immuno-interactive with a polypeptide or modulatory agent as broadly described above, and a detector polynucleotide or oligonucleotide that hybridises to said expression product in a kit for assessing the responsiveness of animal cells to treatment with at least one interferon (IFN).

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation showing a cytotoxic T lymphocyte response to a cancer cell.

FIG. 2 is a graphical representation showing the effect of interferon treatment on MHC Class I expression on the surface of B16 murine melanoma cells.

FIG. 3A is a graphical representation showing the levels of B7-1 on B16 wild type cells.

FIG. 3B is a graphical representation showing the levels of ICAM-1 on B16 wild type cells.

FIG. 4 is a graphical representation showing the levels of B7-1 on B16 cell lines transfected with a vector expressing B7-1.

FIG. 5A is a graphical representation showing the levels of B7-1 on B16B7-1High cells are unaffected by interferon treatment.

FIG. 5B is a graphical representation showing the levels of ICAM-1 on B16B7-1High cells remain at similar levels relative to those on wild type B16 cells.

FIG. 5C is a graphical representation showing increased levels of MHC Class I on B16B7-1High cells relative to wild type B16 cells.

FIG. 6 is a graphical representation showing increased killing of tumour targets by CTL obtained from animals vaccinated with interferon treated B16B7-1High cells.

FIG. 7 is a graphical representation showing the effect of B7 expression and interferon treatment on stimulator populations and on target cells.

FIG. 8A is a graphical representation showing the combined effect of B7 expression and interferon treatment on the resulting in vitro CTL response.

FIG. 8B is a graphical representation showing the combined effect of B7.1 expression and interferon treatment on the resulting in vitro CTL response.

FIG. 9 is a graphical representation showing the immune effector population in the MLCs from mice vaccinated with B16-F10/B7-1^(hi) cells comprises CD8+ CTLs. Samples of MLC populations prepared from mice vaccinated with B16-F10/B7-1^(hi) cells were either used whole (-▪-) or subjected to cell affinity purification with either anti-murine CD4 (-∘-) or anti-CD8 (-⋄-) mAbs on Dynabeads and the different cell populations assayed for in vitro cytotoxic activity using 51-chromium loaded B16-F10/B7-1^(hi) cells as targets. Error bars±S.D.

FIG. 10 is a graphical representation showing killing of different target cells by CTL obtained from animals vaccinated with interferon treated B16B7-1High cells.

FIG. 11 is a graphical representation showing the results of analyses of CTL responses obtained when Balb/c mice were used as the allogeneic control system compared to the responses obtained in C57B16 syngeneic mice.

FIG. 12 is a graphical representation showing an example of a comparative analysis of the immune responses obtained in allogeneic versus syngeneic mice injected with the B7Hi interferon treated B16 vaccine, and analysed after stimulation on B7Hi interferon treated B16 cells using B7Hi interferon treated target cells.

FIG. 13 is a graphical representation showing the results of preclinical trials using the immunopotentiating composition of the invention as a vaccine.

FIG. 14A is a graphical representation showing the effects of IFN-gamma/-beta treatment and B7-1 expression on the susceptibility of B16-F10 cells to cytotoxic killing. MLCs prepared from mice vaccinated with B16-F10/17^(hi) cells were examined for their ability to kill preparations of B16-F10 target cells differing in their expression of B7-1 and treatment with IFNs and were measured using in vitro cytotoxicity assays. Error bars±S.D. The target cells were as follows: control untreated B16-F10 cells (-⋄-); B16-F10 cells treated with IFN-gamma/-beta (-∘-); B16-F10/B7-1^(hi) cells (-□-) and B16-F10/B7-1^(hi) cells treated with IFN-gamma/-beta (-Δ-).

FIG. 14B is a graphical representation showing quantitative comparison of the susceptibility of different B16-F10 cell preparations to cytotoxic activity derived from mice vaccinated with IFN-gamma/-beta treated B16-F10/B7-1^(hi) cells. The results in A were analysed according to the method of Wunderlich and Shearer (41) with one lytic unit defined as the relative number of effectors required to produce 15% cytolysis. Error bars±S.D. The target cells were as follows: B16-F10 cells treated with IFN-gamma/-beta (-∘-); B16-F10/B7-1^(hi) cells (-□-); B16-F10/B7-1^(hi) cells treated with IFN-gamma/-beta (-Δ-).

FIG. 15 is a graphical representation showing MLC cytotoxic effector cell specificity for B16-F10 melanoma versus syngeneic EL-4 thymoma cell target populations. MLCs from age and sex matched C57BL/6Jmice vaccinated with either EL-4 cells or with IFN-gamma/-beta treated B16-F10/B₇-1^(hi) cells were tested by in vitro cytotoxicity assay for their ability to kill different target cell populations. Error bars±S.D. The target cells were as follows: IFN-gamma/-beta treated B16-F10/B7-1^(hi) cell vaccine, stimulators and target cells (-▴-); EL-4 cell vaccine and stimulators, IFN treated B16-F10/B7-1^(hi) target cells (-▪-); IFN-gamma/-beta treated B16-F10/B7-1^(hi) cell vaccine and stimulators, EL-4 target cells (-∘-); EL-4 cell vaccine, stimulators and target cells (-⋄-).

BRIEF DESCRIPTION OF THE SEQUENCES: SUMMARY TABLE

TABLE A SEQUENCE ID NUMBER SEQUENCE LENGTH SEQ ID NO: 1 Full-length human CDS encoding 501 nts interferon gamma as set forth under GenBank Accession No. J00219 SEQ ID NO: 2 Polypeptide encoded by SEQ ID NO: 1 166 aa SEQ ID NO: 3 Full-length human CDS encoding 564 nts interferon beta 1 as set forth under GenBank Accession No. 11428335 SEQ ID NO: 4 Polypeptide encoded by SEQ ID NO: 3 187 aa SEQ ID NO: 5 Full-length human CDS encoding 639 nts interferon beta 2 as set forth under GenBank Accession No. 32673 SEQ ID NO: 6 Polypeptide encoded by SEQ ID NO: 5 212 aa SEQ ID NO: 7 Full-length human CDS encoding 567 nts interferon alpha as set forth under GenBank Accession No. M54886 SEQ ID NO: 8 Polypeptide encoded by SEQ ID NO: 7 188 aa SEQ ID NO: 9 Full-length human CDS encoding 570 nts interferon alpha 1 as set forth under GenBank Accession No. 11429098 SEQ ID NO: 10 Polypeptide encoded by SEQ ID NO: 9 189 aa SEQ ID NO: 11 Full-length human CDS encoding 567 nts interferon alpha 2 as set forth under GenBank Accession No. 12734961 SEQ ID NO: 12 Polypeptide encoded by SEQ ID NO: 11 188 aa SEQ ID NO: 13 Full-length human CDS encoding B7-1 as 867 nts set forth under GenBank Accession No. 4885122 SEQ ID NO: 14 Polypeptide encoded by SEQ ID NO: 13 288 aa SEQ ID NO: 15 Full-length human CDS encoding B7-2 as 972 nts set forth under GenBank Accession No. 5901919 SEQ ID NO: 16 Polypeptide encoded by SEQ ID NO: 15 323 aa SEQ ID NO: 17 CDS encoding Sus scrofa B7-1 protein 690 nts precursor as set forth under GenBank Accession No. AF203442 SEQ ID NO: 18 Polypeptide encoded by SEQ ID NO: 17 229 aa SEQ ID NO: 19 CDS encoding soluble human B7-1 702 nts protein precursor SEQ ID NO: 20 Polypeptide encoded by SEQ ID NO: 19 233 aa

DETAILED DESCRIPTION OF THE INVENTION

1. Definitions

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the-present invention, preferred methods and materials are described. For the purposes of the present invention, the following terms are defined below.

The articles “a” and “an” are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.

The term “about” is used herein to refer to conditions (e.g. amounts, concentrations, time etc) that vary by as much as 30%, preferably by as much as 20%, and more preferably by as much as 10% to a specified condition.

The terms “administration simultaneously” or “administering simultaneously” refer to the administration of a single composition containing both an immunostimulatory molecule and interferon treated animal cell, or the administration of each active as separate compositions and/or delivered by separate routes within a short enough period of time that the effective result is equivalent to that obtained when both such actives are administered as a single composition.

By “agent” is meant a naturally occurring or synthetically produced molecule which interacts either directly or indirectly with a target member, the level and/or functional activity of which are to be modulated.

The term “analogue” refers to a molecule substantially similar in function to a reference molecule or to a biologically active fragment thereof.

By “antigen-binding molecule” is meant a molecule that has binding affinity for a target antigen. It will be understood that this term extends to immunoglobulins, immunoglobulin fragments and non-immunoglobulin derived protein frameworks that exhibit antigen-binding activity.

By “autologous” is meant something (e.g., cells, tissues etc) derived from the same organism.

The term “allogeneic” as used herein refers to cells, tissues, organisms etc that are of different genetic constitution.

By “biologically active fragment” is meant a fragment of a full-length parent polypeptide which fragment retains the activity of the parent polypeptide. A biologically active fragment will, therefore, inter alia have a biological activity of a parent polypeptide selected from an interferon alpha, an interferon beta, an interferon gamma, a B7-1 molecule and a B7-2 molecule. As used herein, the term “biologically active fragment” includes deletion mutants and small peptides, for example of at least 8, preferably at least 10, more preferably at least 15, even more preferably at least 20 and even more preferably at least 30 contiguous amino acids, which comprise the above activities. Peptides of this type may be obtained through the application of standard recombinant nucleic acid techniques or synthesised using conventional liquid or solid phase synthesis techniques. For example, reference may be made to solution synthesis or solid phase synthesis as described, for example, in Chapter 9 entitled “Peptide Synthesis” by Atherton and Shephard which is included in a publication entitled “Synthetic Vaccines” edited by Nicholson and published by Blackwell Scientific Publications. Alternatively, peptides can be produced by digestion of a polypeptide of the invention with proteinases such as endoLys-C, endoArg-C, endoGlu-C and staphylococcus V8-protease. The digested fragments can be purified by, for example, high performance liquid chromatographic (HPLC) techniques.

As used herein, a “cellular composition”, “cellular vaccine” or “cellular immunogen” refers to a composition comprising at least one cell population, which is optionally inactivated, as an active ingredient.

Throughout this specification, unless the context requires otherwise, the words “comprise”, “comprises” and “comprising” will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements.

By “corresponds to” or “corresponding to” is meant a polynucleotide (a) having a nucleotide sequence that is substantially identical or complementary to all or a portion of a reference polynucleotide sequence or (b) encoding an amino acid sequence identical to an amino acid sequence in a peptide or protein. This phrase also includes within its scope a peptide or polypeptide having an amino acid sequence that is substantially identical to a sequence of amino acids in a reference peptide or protein.

By “derivative” is meant a polypeptide that has been derived from the basic sequence by modification, for example by conjugation or complexing with other chemical moieties or by post-translational modification techniques as would be understood in the art. The term “derivative” also includes within its scope alterations that have been made to a parent sequence including additions, or deletions that provide for functionally equivalent molecules.

To enhance immune response (“immunoenhancement”), as is well-known in the art, means to increase the animal's capacity to respond to foreign or disease-specific antigens (e.g., cancer antigens) i.e., those cells primed to attack such antigens are increased in number, activity, and ability to detect and destroy the those antigens. Strength of immune response is measured by standard tests including: direct measurement of peripheral blood lymphocytes by means known to the art; natural killer cell cytotoxicity assays (see, e.g., Provinciali M. et al (1992, J. Immunol. Meth. 155: 19-24), cell proliferation assays (see, e.g., Vollenweider, I. And Groseurth, P. J. (1992, J. Immunol. Meth. 149: 133-135), immunoassays of immune cells and subsets (see, e.g., Loeffler, D. A., et al. (1992, Cytom. 13: 169-174); Rivoltini, L., et al. (1992, Can. Immunol. Immunother. 34: 241-251); or skin tests for cell-mediated immunity (see, e.g., Chang, A. E. et al (1993, Cancer Res. 53: 1043-1050). Any statistically significant increase in strength of immune response as measured by the foregoing tests is considered “enhanced immune response” “immunoenhancement” or “immunopotentiation” as used herein. Enhanced immune response is also indicated by physical manifestations such as fever and inflammation, as well as healing of systemic and local infections, and reduction of symptoms in disease, i.e., decrease in tumour size, alleviation of symptoms of a disease or condition including, but not restricted to, leprosy, tuberculosis, malaria, naphthous ulcers, herpetic and papillomatous warts, gingivitis, artherosclerosis, the concomitants of AIDS such as Kaposi's sarcoma, bronchial infections, and the like. Such physical manifestations also define “enhanced immune response” “immunoenhancement” or “immunopotentiation” as used herein.

As used herein, the term “function” refers to a biological, enzymatic, or therapeutic function.

By “greatly increased levels” or “high levels” in the context of molecular expression is meant expression of a molecule at levels that are 10-fold, more preferably 50-fold, more preferably 100-fold and more preferably 200-fold above a reference level. For example, B16High cells as used herein, express greatly increased levels of a B7 molecule on their surface, which levels are 10-fold, more preferably 50-fold, more preferably 100-fold and more preferably 200-fold above wild-type B16 cells.

“Homology” refers to the percentage number of amino acids that are identical or constitute conservative substitutions as defined in Table A infra. Homology may be determined using sequence comparison programs such as GAP (Deveraux et al. 1984, Nucleic Acids Research 12, 387-395). In this way, sequences of a similar or substantially different length to those cited herein might be compared by insertion of gaps into the alignment, such gaps being determined, for example, by the comparison algorithm used by GAP.

“Hybridisation” is used herein to denote the pairing of complementary nucleotide sequences to produce a DNA-DNA hybrid or a DNA-RNA hybrid. Complementary base sequences are those sequences that are related by the base-pairing rules. In DNA, A pairs with T and C pairs with G. In RNA U pairs with A and C pairs with G. In this regard, the terms “match” and “mismatch” as used herein refer to the hybridisation potential of paired nucleotides in complementary nucleic acid strands. Matched nucleotides hybridise efficiently, such as the classical A-T and G-C base pair mentioned above. Mismatches are other combinations of nucleotides that do not hybridise efficiently.

Reference herein to “immuno-interactive” includes reference to any interaction, reaction, or other form of association between molecules and in particular where one of the molecules is, or mimics, a component of the immune system.

“Inactivation” of a cell is used herein to indicate that the cell has been rendered incapable of cell division to form progeny. The cell may nonetheless be capable of response to stimulus, or biosynthesis and/or secretion of cell products such as cytokines. Methods of inactivation are known in the art. Preferred methods of inactivation are treatment with toxins such as mitomycin C, or irradiation. Cells that have been fixed or permeabilised and are incapable of division are also examples of inactivated cells.

By “isolated” is meant material that is substantially or essentially free from components that normally accompany it in its native state.

A composition is “immunogenic” if it is capable of either: a) generating an immune response against an antigen (e.g., a tumour antigen) in a naive individual; or b) reconstituting, boosting, or maintaining an immune response in an individual beyond what would occur if the compound or composition was not administered. A composition is immunogenic if it is capable of attaining either of these criteria when administered in single or multiple doses.

By “modulating” is meant increasing or decreasing, either directly or indirectly, the level and/or functional activity of a target molecule. For example, an agent may indirectly modulate the said level/activity by interacting with a molecule other than the target molecule. In this regard, indirect modulation of a gene encoding a target polypeptide includes within its scope modulation of the expression of a first nucleic acid molecule, wherein an expression product of the first nucleic acid molecule modulates the expression of a nucleic acid molecule encoding the target polypeptide.

By “obtained from” is meant that a sample such as, for example, a nucleic acid extract or polypeptide extract is isolated from, or derived from, a particular source of the host. For example, the extract may be obtained from a tissue or a biological fluid isolated directly from the host.

The term “oligonucleotide” as used herein refers to a polymer composed of a multiplicity of nucleotide units (deoxyribonucleotides or ribonucleotides, or related structural variants or synthetic analogues thereof) linked via phosphodiester bonds (or related structural variants or synthetic analogues thereof). Thus, while the term “oligonucleotide” typically refers to a nucleotide polymer in which the nucleotides and linkages between them are naturally occurring, it will be understood that the term also includes within its scope various analogues including, but not restricted to, peptide nucleic acids (PNAs), phosphoramidates, phosphorothioates, methyl phosphonates, 2-O-methyl ribonucleic acids, and the like. The exact size of the molecule may vary depending on the particular application. An oligonucleotide is typically rather short in length, generally from about 10 to 30 nucleotides, but the term can refer to molecules of any length, although the term “polynucleotide” or “nucleic acid” is typically used for large oligonucleotides.

By “operably linked” is meant that transcriptional and translational regulatory nucleic acids are positioned relative to a polypeptide-encoding polynucleotide in such a manner that the polynucleotide is transcribed and the polypeptide is translated.

The term “patient” refers to patients of human or other mammal and includes any individual it is desired to examine or treat using the methods of the invention. However, it will be understood that “patient” does not imply that symptoms are present. Suitable mammals that fall within the scope of the invention include, but are not restricted to, primates, livestock animals (e.g., sheep, cows, horses, donkeys, pigs), laboratory test animals (e.g., rabbits, mice, rats, guinea pigs, hamsters), companion animals (e.g., cats, dogs) and captive wild animals (e.g., foxes, deer, dingoes).

By “pharmaceutically-acceptable carrier” is meant a solid or liquid filler, diluent or encapsulating substance that may be safely used in topical or systemic administration.

The term “polynucleotide” or “nucleic acid” as used herein designates mRNA, RNA, cRNA, cDNA or DNA. The term typically refers to oligonucleotides greater than 30 nucleotides in length.

The terms “polynucleotide variant” and “variant” refer to polynucleotides displaying substantial sequence identity with a reference polynucleotide sequence or polynucleotides that hybridise with a reference sequence under stringent conditions that are defined hereinafter. These terms also encompasses polynucleotides in which one or more nucleotides have been added or deleted, or replaced with different nucleotides. In this regard, it is well understood in the art that certain alterations inclusive of mutations, additions, deletions and substitutions can be made to a reference polynucleotide whereby the altered polynucleotide retains the biological function or activity of the reference polynucleotide. The terms “polynucleotide variant” and “variant” also include naturally occurring allelic variants.

“Polypeptide”, “peptide” and “protein” are used interchangeably herein to refer to a polymer of amino acid residues and to variants and synthetic analogues of the same. Thus, these terms apply to amino acid polymers in which one or more amino acid residues is a synthetic non-naturally occurring amino acid, such as a chemical analogue of a corresponding naturally occurring amino acid, as well as to naturally-occurring amino acid polymers.

The term “polypeptide variant” refers to polypeptides which vary from a reference polypeptide by the addition, deletion or substitution of at least one amino acid. It is well understood in the art that some amino acids may be changed to others with broadly similar properties without changing the nature of the activity of the polypeptide. Accordingly, polypeptide variants as used herein encompass polypeptides that have similar activities to a parent polypeptide selected from an interferon alpha, an interferon beta, an interferon gamma, a B7-1 molecule and a B7-2 molecule. Preferred variant polypeptides comprise conservative amino acid substitutions. Exemplary conservative substitutions in a polypeptide may be made according to the following table:

TABLE B Original Residue Exemplary Substitutions Ala Ser Arg Lys Asn Gln, His Asp Gln Cys Ser Gln Asn Glu Asp Gly Pro His Asn, Gln Ile Leu, Val Leu Ile, Val Lys Arg, Gln, Glu Met  Leu, Ile, Phe Met, Leu, Tyr Ser Thr Thr Ser Trp Tyr Tyr Trp, Phe Val Ile, Leu

Substantial changes in function are made by selecting substitutions that are less conservative than those shown in TABLE B. Other replacements would be non-conservative substitutions and relatively fewer of these may be tolerated. Generally, the substitutions which are likely to produce the greatest changes in a polypeptide's properties are those in which (a) a hydrophilic residue (e.g., Ser or Asn) is substituted for, or by, a hydrophobic residue (e.g., Ala, Leu, Ile, Phe or Val); (b) a cysteine or proline is substituted for, or by, any other residue; (c) a residue having an electropositive side chain (e.g., Arg, His or Lys) is substituted for, or by, an electronegative residue (e.g., Glu or Asp) or (d) a residue having a smaller side chain (e.g., Ala, Ser) or no side chain (e.g., Gly) is substituted for, or by, one having a bulky side chain (e.g., Phe or Trp).

By “primer” is meant an oligonucleotide which, when paired with a strand of DNA, is capable of initiating the synthesis of a primer extension product in the presence of a suitable polymerising agent. The primer is preferably single-stranded for maximum efficiency in amplification but may alternatively be double-stranded. A primer must be sufficiently long to prime the synthesis of extension products in the presence of the polymerisation agent. The length of the primer depends on many factors, including application, temperature to be employed, template reaction conditions, other reagents, and source of primers. For example, depending on the complexity of the target sequence, the oligonucleotide primer typically contains 15 to 35 or more nucleotides, although it may contain fewer nucleotides. Primers can be large polynucleotides, such as from about 200 nucleotides to several kilobases or more. Primers may be selected to be “substantially complementary” to the sequence on the template to which it is designed to hybridise and serve as a site for the initiation of synthesis. By “substantially complementary”, it is meant that the primer is sufficiently complementary to hybridise with a target nucleotide sequence. Preferably, the primer contains no mismatches with the template to which it is designed to hybridise but this is not essential. For example, non-complementary nucleotides may be attached to the 5′ end of the primer, with the remainder of the primer sequence being complementary to the template. Alternatively, non-complementary nucleotides or a stretch of non-complementary nucleotides can be interspersed into a primer, provided that the primer sequence has sufficient complementarity with the sequence of the template to hybridise therewith and thereby form a template for synthesis of the extension product of the primer.

“Probe” refers to a molecule that binds to a specific sequence or sub-sequence or other moiety of another molecule. Unless otherwise indicated, the term “probe” typically refers to a polynucleotide probe that binds to another nucleic acid, often called the “target nucleic acid”, through complementary base pairing. Probes may bind target nucleic acids lacking complete sequence complementarity with the probe, depending on the stringency of the hybridisation conditions. Probes can be labelled directly or indirectly.

The term “recombinant polynucleotide” as used herein refers to a polynucleotide formed in vitro by the manipulation of nucleic acid into a form not normally found in nature. For example, the recombinant polynucleotide may be in the form of an expression vector. Generally, such expression vectors include transcriptional and translational regulatory nucleic acid operably linked to the nucleotide sequence.

By “recombinant polypeptide” is meant a polypeptide made using recombinant techniques, i.e., through the expression of a recombinant polynucleotide.

By “reporter molecule” as used in the present specification is meant a molecule that, by its chemical nature, provides an analytically identifiable signal that allows the detection of a complex comprising an antigen-binding molecule and its target antigen. The term “reporter molecule” also extends to use of cell agglutination or inhibition of agglutination such as red blood cells on latex beads, and the like.

As used herein “stimulating” an immune or immunological response refers to administration of a composition that initiates, boosts, or maintains the capacity for the host's immune system to react to a target substance, such as a foreign molecule, an allogeneic cell, or a tumour cell, at a level higher than would otherwise occur. Stimulating a “primary” immune response refers herein to eliciting specific immune reactivity in a subject in which previous reactivity was not detected; for example, due to lack of exposure to the target antigen, refractoriness to the target, or immune suppression. Stimulating a “secondary” response refers to the reinitiation, boosting, or maintenance of reactivity in a subject in which previous reactivity was detected; for example, due to natural immunity, spontaneous immunisation, or treatment using one or several compositions or procedures.

By “therapeutically effective amount”, in the context of treating a condition, is meant the administration of that amount of immunopotentiating composition that elicits an immune response in an individual in need of such treatment, either in a single dose or as part of a series, that is effective for treatment of that condition. The effective amount will vary depending upon the health and physical condition of the individual to be treated, the taxonomic group of individual to be treated, the formulation of the composition, the assessment of the medical situation, and other relevant factors. It is expected that the amount will fall in a relatively broad range that can be determined through routine trials.

The term “valency” as used herein refers to the number of binding sites available per molecule.

By “vector” is meant a nucleic acid molecule, preferably a DNA molecule derived, for example, from a plasmid, bacteriophage, or plant virus, into which a nucleic acid sequence may be inserted or cloned. A vector preferably contains one or more unique restriction sites and may be capable of autonomous replication in a defined host cell including a target cell or tissue or a progenitor cell or tissue thereof, or be integrable with the genome of the defined host such that the cloned sequence is reproducible. Accordingly, the vector may be an autonomously replicating vector, i.e., a vector that exists as an extrachromosomal entity, the replication of which is independent of chromosomal replication, e.g., a linear or closed circular plasmid, an extrachromosomal element, a minichromosome, or an artificial chromosome. The vector may contain any means for assuring self-replication. Alternatively, the vector may be one which, when introduced into the host cell, is integrated into the genome and replicated together with the chromosome(s) into Which it has been integrated. A vector system may comprise a single vector or plasmid, two or more vectors or plasmids, which together contain the total DNA to be introduced into the genome of the host cell, or a transposon. The choice of the vector will typically depend on the compatibility of the vector with the host cell into which the vector is to be introduced. The vector may also include a selection marker such as an antibiotic resistance gene that can be used for selection of suitable transformants. Examples of such resistance genes are well known to those of skill in the art.

2. Abbreviations

The following abbreviations are used in the present specification.

aa Amino acid(s) CDS Coding sequence IFN Interferon IFN-alpha alpha-Interferon IFN-beta beta-Interferon IFN-gamma gamma-Interferon Ig Immunoglobulin IL Interleukin ISGF3gamma IFN-stimulated gene factor 3 (ISGF3 gamma is a transcription factor which is a complex of STAT molecules including STAT1 and STAT2 (31)) ISRE IFN-stimulated response element JAK-1 Janus Kinase-1 MAbs Monoclonal antibodies MHC Major Histocompatability Complex MLC Mixed lymphocyte cultures MLR Mixed lymphocyte reaction nts nucleotides p48-ISGF3gamma A component of ISGF-3 induced by gamma interferon STAT Signal transducers and activators of transcription TYK-2 Tyrosine Kinase-2 3. Immunopotentiating Compositions

The present invention stems at least in part from the discovery that there is a synergistic enhancement in immunopotentiation of animal cells by culturing the animal cells in the presence of at least one interferon followed by washing the animal cells to remove the interferon(s), wherein the animal cells express on their surface, or are otherwise provided in combination, an immunostimulatory molecule.

The invention thus provides in one aspect a method for enhancing immunopotentiation of animal cells, comprising culturing animal cells with at least one interferon for a time and under conditions sufficient to enhance the antigen presenting function of the cells and washing the animal cells to remove the at least one interferon, wherein the cells express on their surface, or are otherwise provided in combination, an immunostimulatory molecule.

In a preferred embodiment, the method further comprises isolating cells expressing said immunostimulatory molecule from a heterogeneous population of animal cells. Any method of isolation is contemplated by the present invention. Suitable methods for isolating particular cells are known to those of skill in the art. For example, one can take advantage of one or more particular characteristics of a cell to specifically isolate that cell from a heterogeneous population. Such characteristics include, but are not limited to, anatomical location of a cell, cell density, cell size, cell morphology, cellular metabolic activity, cell uptake of ions such as Ca²⁺, K⁺, and H⁺ ions, cell uptake of compounds such as stains, markers expressed on the cell surface, protein fluorescence, and membrane potential. Suitable methods that can be used in this regard include surgical removal of tissue, flow cytometry techniques such as fluorescence-activated cell sorting (FACS), immunoaffinity separation (e.g., magnetic bead separation such as Dynabead™ separation), density separation (e.g., metrizamide, Percoll™, or Ficoll™ gradient centrifugation), and cell-type specific density separation.

In the present case, the cells are preferably isolated by flow cytometry or by immunoaffinity separation using an antigen-binding molecule that is immuno-interactive with the immunostimulatory molecule.

According to an alternate embodiment, the method further comprises modifying the animal cells to express on their surface the immunostimulatory molecule. Thus, the immunostimulatory molecule can be an immunostimulatory membrane molecule, wherein at least a portion of said molecule is exposed to the extracellular environment (i.e., the exterior of a respective cell). In this instance, the immunostimulatory molecule is preferably an immunostimulatory membrane molecule, which is suitably a T cell co-stimulatory molecule. In one embodiment, the T cell co-stimulatory molecule is a B7 molecule, or biologically active fragment thereof, or variant or derivative of these. The B7 molecule includes, but is not restricted to, B7-1 and B7-2. Preferably, the B7 molecule is B7-1. Suitable polypeptide sequences for B7-1 and B7-2 include, but are not restricted to, those set forth respectively in SEQ ID NO: 14 and 16, including biologically-active fragments thereof, and variants or derivatives of these. In an alternate embodiment, the T cell co-stimulatory molecule is an ICAM molecule such as ICAM-1 and ICAM-2.

Preferably, the step of modification comprises introducing into said animal cells a polynucleotide from which the immunostimulatory molecule can be translated. Suitably, the polynucleotide is operably linked to a regulatory polynucleotide preferably in the form of an expression vector. Regulatory polynucleotides which can be utilised to regulate expression of the polynucleotide include, but are not limited to, a promoter, an enhancer, and a transcription terminator. Such regulatory polynucleotides are known to those of skill in the art. The expression vector preferably comprises at least one promoter. Suitable promoters that can be utilised to induce expression of the polynucleotide include constitutive promoters and inducible promoters.

Any suitable polynucleotide encoding the B7 molecule can be employed. Polynucleotides encoding B7-1 molecules which can be utilised in accordance with the invention are described, for example, in Freeman et al. (1989, J. Immunol. 143: 2714-2722), Freeman et al. (1992, Blood 79: 489-494), and in the GenBank database under locus designations HUMIGB7 (Accession number M27533) and NM_(—)005191 (Accession number NM_(—)005191). An exemplary polynucleotide sequence encoding B7-1 is set forth in SEQ ID NO: 13. Suitable polynucleotides encoding B7-2 molecules are described, for example, in Azuma et al. (1993, Nature 336: 76-79), Chen et al. (1994, J Immunol. 152: 4929-4963), and in the GenBank database under locus designation NM_(—)006889 (Accession number NM_(—)006889). A suitable B7-2 encoding polynucleotide is set forth in SEQ ID NO: 15.

An exemplary expression vector for expression of the immunostimulatory protein includes the herpes simplex amplicons described for example by Fong et al. in U.S. Pat. No. 6,051,428.

It will be understood by persons of skill in the art that the techniques for assembling and expressing DNA encoding the immunostimulatory molecule, e.g., synthesis of oligonucleotides, nucleic acid amplification techniques, transforming cells, constructing vectors, expression systems, and the like and transducing or otherwise introducing such DNA into animal cells are well-established in the art, and most practitioners are familiar with the standard resource materials for specific conditions and procedures.

In another embodiment, the immunostimulatory molecule is suitably in soluble form. In a preferred embodiment of this type, the immunostimulatory protein is a B7 molecule that lacks a functional transmembrane domain. Preferably, the soluble B7 molecule comprises a B7 extracellular domain. Soluble B7-1 molecules of this type are disclosed, for example, by McHugh et al. (1998, Clin. Immunol. Immunopathol. 87(1): 50-59), Faas et al. (2000, J. Immunol. 164(12): 6340-6348) and Jeannin et al. (2000, Immunity 13(3): 303-312). Examples of polypeptide sequences for soluble B7-1 include, but are not limited to, those set forth in SEQ ID NO: 18 and 20, including biologically-active fragments thereof, and variants or derivatives of these. In another preferred embodiment of this type, the immunostimulatory protein is a B7 derivative. The B7 derivative is suitably a chimeric or fusion protein comprising a B7 molecule, or biologically active fragment thereof, or variant or derivative of these, linked together with an antigen binding molecule which is preferably an immunoglobulin molecule or biologically active fragment thereof.

Preferred chimeric proteins in accordance with the present invention include chimeric proteins which comprise a polypeptide corresponding to a biologically active fragment of a B7 molecule. For example, a derivative of a B7 molecule useful in the method of the present invention is a B7Ig fusion protein that comprises a polypeptide corresponding to the extracellular domain of the B7 molecule and an immunoglobulin constant region that alters the solubility, affinity and/or valency of the B7 molecule.

In a preferred embodiment, a polynucleotide encoding the amino acid sequence corresponding to the extracellular domain of the B7-1 molecule, containing amino acids from about position 1 to about position 215, is joined to a polynucleotide encoding the amino acid sequences corresponding to the hinge, CH2 and CH3 regions of human Ig Cγ1, using PCR, to form a construct that is expressed as a B7Ig fusion protein. DNA encoding the amino acid sequence corresponding to a B7Ig fusion protein has been deposited with the American Type culture Collection (ATCC) in Rockville, Md., under the Budapest Treaty on May 31, 1991 and accorded accession number 68627. Techniques for making and assembling such B7 derivatives are disclosed for example by Linsley et al. (U.S. Pat. No. 5,580,756). Reference also may be made to Sturmhoefel et al. (1999, Cancer Res. 59: 4964-4972) who disclose fusion proteins comprising the extracellular region of B7-1 or B7-2 fused in frame to the Fc portion of IgG2a.

The half-life of a soluble immunostimulatory protein may be prolonged by any suitable procedure if desired. Preferably, such molecules are chemically modified with polyethylene glycol (PEG), including monomethoxy-polyethylene glycol, as for example disclosed by Chapman et al (1999, Nature Biotechnology 17: 780-783).

The step of culturing may comprise contacting said cells with at least one type I interferon and/or a type II interferon. The at least one type I interferon is preferably selected from the group consisting of an IFN-alpha, an IFN-beta, a biologically active fragment of an IFN-alpha, a biologically active fragment of an IFN-beta, a variant of an IFN-alpha, a variant of an IFN-beta, a variant of a said biologically active fragment, a derivative of an IFN-alpha, a derivative of an IFN-beta, a derivative of a said biologically active fragment, a derivative of a said variant, an analogue of IFN-alpha and an analogue of IFN-beta. Preferably, the type II interferon is selected from the group consisting of an IFN-gamma, a biologically active fragment of an IFN-gamma, a variant of an IFN-gamma, a variant of said biologically active fragment, a derivative of an IFN-gamma, a derivative of said biologically active fragment, a derivative of said variant and an analogue of an IFN-gamma.

Suitably, the IFN-gamma comprises the amino acid sequence set forth in SEQ ID NO: 2.

In one embodiment, the IFN-beta is an IFN-beta 1, which suitably comprises the amino acid sequence set forth in SEQ ID NO: 4. In an alternate embodiment, the IFN-beta is an IFN-beta 2, which preferably comprises the amino acid sequence set forth in SEQ ID NO: 6.

In one embodiment, the IFN-alpha comprises the amino acid sequence set forth in SEQ ID NO: 8. In an alternate embodiment, the IFN-alpha is an IFN-alpha 1, which suitably comprises the amino acid sequence set forth in SEQ ID NO: 10. In yet another embodiment, the IFN-alpha is an IFN-alpha 2, which suitably comprises the amino acid sequence set forth in SEQ ID NO: 12.

For example, IFN-alpha and/or IFN-beta may be used directly on the cells or the cells may first be cultured in the presence of IFN-gamma prior to treatment with IFN-alpha and/or IFN-beta. Although not intending to limit the present invention to any one theory or particular mode of action, it is proposed this IFN-gamma restores or enhances levels of transcriptional factors required for transcriptional activation of genes regulated by IFN-alpha and IFN-beta.

Accordingly, the step of culturing preferably comprises contacting said cells with a type II IFN for a time and under conditions sufficient to permit cellular responsiveness to at least one type I interferon and then contacting said cultured cells with the at least one type I IFN for a time and under conditions sufficient to enhance the antigen presenting function of said cells.

In one embodiment, the cells cultured in the presence of the type II IFN are contacted with a type I IFN selected from the group consisting of an IFN-beta, a biologically active fragment of an IFN-beta, a variant of an IFN-beta, a variant of a said biologically active fragment, a derivative of an IFN-beta, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-beta.

In another embodiment, the cells cultured in the presence of the type II IFN are contacted with a type I IFN selected from the group consisting of an IFN-alpha, a biologically active fragment of an IFN-alpha, a variant of an IFN-alpha, a variant of a said biologically active fragment, a derivative of an IFN-alpha, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-alpha.

In yet another embodiment, the cells cultured in the presence of the type II IFN are contacted with a first type I IFN selected from the group consisting of an IFN-beta, a biologically active fragment of an IFN-beta, a variant of an IFN-beta, a variant of a said biologically active fragment, a derivative of an IFN-beta, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-beta, and a second type I interferon selected from the group consisting of an IFN-alpha, a biologically active fragment of an IFN-alpha, a variant of an IFN-alpha, a variant of a said biologically active fragment, a derivative of an IFN-alpha, a derivative of a said biologically active fragment, a derivative of a said variant and an analogue of an IFN-alpha.

Suitably, the cells are cultured with a type II IFN (e.g., IFN-gamma), from about 16 to about 96 hours and subsequently with one or more type I interferons (e.g., IFN-alpha and/or IFN-beta) from about 16 to about 72 hours. Preferably, the cells are cultured with a type II IFN (e.g., IFN-gamma) from about 48 to about 96 hours and subsequently with one or more type I interferons (e.g., IFN-alpha and/or IFN-beta) from about 24 to about 72 hours.

The cells may be treated with IFN-gamma at a concentration of about 100 to about 2000 international units/mL and subsequently with IFN-alpha and/or IFN-beta at a concentration of about 100 to about 2000 international units/mL. Preferably, the cells are cultured with IFN-gamma at a concentration of about 1000 international units/mL and subsequently with IFN-alpha and/or IFN-beta at a concentration of about 1000 international units/mL.

It will be appreciated that the animal cells are, therefore, subjected to at least one IFN in concentrated form unattainable in a recipient host. Not wishing to be bound by any one particular theory or mode of action, the culturing in the presence of the at least one IFN potentiates both the ability of the animal cells to process antigens via antigen processing pathways and to present the processed antigens on the cell surface. The presence of the immunostimulatory molecule, which is preferably a T cell co-stimulatory molecule, on the surface of the animal cells, or in combination therewith, provides the means to effect T cell activation through, for example, the CD28 or CTLA4 receptors present on T cells.

Preferably, the step of culturing further comprises expanding the population of isolated cells in culture. Such expansion techniques are known to those of skill in the art. For example, the expanded population of cells as described infra is prepared from isolated cells grown in flasks. The production of the expanded population can, if desired, be scaled up by culturing the cells in bioreactors or fermentors or other such vessels or devices suitable for the growing of cells in bulk. The isolated population is preferably expanded in the presence of suitable complete growth media (for example, RPMI OR DMEM containing 10% foetal calf sera or serum free media) in the presence of one or more cytokines/growth factors including, but not restricted to, fibroblast growth factor, at 37° C., 5-7% carbon dioxide.

One particular advantage of the present invention is that no predetermined selection of the types of antigens presented on the cells occurs since the cells are used as a source of immunogen. Accordingly, a large array of the antigens normally processed by the cells will be available to activate immune cell processes, resulting in a wide variation in the populations of responding immune cells to the range of different antigenic targets. By way of example, a cancer cell will expresses multiple tumour-associated antigens shared by the tumour of a patient to be treated.

Furthermore, antigens are presented in the configuration evolved through natural selection, which is used by antigen presenting cells and, hence, provides for strong immune cell activation. Alternatively, treated cells may be loaded with particular antigenic peptides, which are preferably tumour antigens, to yield specific targeted vaccines. For example, reference may be made to Van Pel et al (1995, Immunol Rev 145: 229-50) who describe various genes encoding tumour antigens recognised by CTL. Reference also may be made to Itoh et al (1994, J. Immunol. 153: 1202-1215) and Cole et al (1995, Cancer Res. 55: 748-752) who describe the use of loading peptides on tumour cells as targets for CTL killing.

Preferred cells are those with a defined MHC genomic region or equivalent and with the capability of increasing or enhancing class I MHC presentation of antigenic molecules to cell surfaces.

The cells of the present invention may be isolated from the intended host, treated and then re-introduced or reinfused into that host. It is particularly convenient to use cells obtained from the host to be treated, either by surgical resection, biopsy, blood sampling, or other suitable technique. Such cells are referred to herein as “autologous” cells. Alternatively, cells or cell lines (e.g., tumour cell lines) may be prepared and/or cultured from one source and introduced into a different host. Such cells are referred to herein as “allogeneic” cells. One particular form of allogeneic cells comprises a generic cell line with shared major and/or minor histocompatibility antigens to potential recipients.

Suitably, the generic cell line naturally expresses the immunostimulatory molecule, preferably an immunostimulatory membrane molecule, at levels sufficient to trigger an immune response, preferably a T cell immune response, and more preferably a cytotoxic T lymphocyte immune response, in the intended host.

It is preferred the generic cell line comprises major histocompatibility (MHC) class I antigens compatible with a high percentage of the population that is susceptible or predisposed to a particular condition. Suitably, the condition being treated or prevented by vaccination is a cancer or tumour. Preferably, the generic cell line expresses high levels of an endogenous B7 molecule. It is also preferred that the generic cell line is highly susceptible to treatment with at least one IFN as described herein (i.e., implied high level expression of class I HLA).

In one embodiment, treated cells (e.g., cancer cells) or cell lines are suitably rendered inactive to prevent further proliferation once administered to the subject. Any physical, chemical, or biological means of inactivation may be used, including but not limited to irradiation (preferably with at least. about 5,000 cGy, more preferably at least about 10,000 cGy, more preferably at least about 20,000 cGy); or treatment with mitomycin-C (preferably at least 10 μg/mL; more preferably at least about 50 μg/mL).

The present invention extends to animal cells from, for example, avian species, reptiles and mammals. Mammals are preferred and include humans, livestock animals (e.g., sheep, cows, horses, pigs), laboratory test animals (e.g., mice, rats, rabbits, guinea pigs), companion animals (e.g., cats, dogs) and captive wild animals (e.g., kangaroos, deer, foxes). Humans are the most preferred animals and both autologous and allogeneic cells may be employed in human subjects.

The animal cells are preferably cancer or tumour cells. The compositions or vaccines in accordance with the present invention would be derived from the tumour or cancer cells. For example, in the treatment of lung cancer in accordance with the practices of this invention, the lung cancer cells would be treated as described hereinabove to produce a lung cancer vaccine. Similarly, breast tumour or cancer cells, prostate cancer cells, colon cancer cells, pancreas cancer cells, stomach cancer cells, bladder cancer cells, kidney cancer cells and the like would be produced and employed as immunotherapeutic agents in accordance with the practices for the prevention and/or treatment of the tumour or cancer cell from which the composition of matter or vaccine according to the invention was produced. In a preferred embodiment, the cancer or tumour cells are preferably selected from the group consisting of melanoma cells and mammary carcinoma cells.

The compositions of matter according to the invention could also be prepared to treat various infectious diseases that affect humans and animals by loading antigens of a pathogenic organism (e.g., viral, bacterial, fungal, protozoan) onto the treated cells. As there is heterogeneity in the type of immunogenic and protective antigens expressed by different varieties of organisms causing the same disease, polyvalent compositions and vaccines could be prepared by preparing the composition or vaccine from a pool of organisms expressing the different antigens of importance. The invention, therefore, also encompasses a method for stimulating a patient's immune system, and preferably for modulating the T cell response of the patient to one or more antigens by administering to the patient animal cells cultured in the presence of at least one interferon (IFN) for a time and under conditions sufficient to enhance the antigen presenting functions of said cells, together with the or each antigen. Accordingly, the immunogenicity of an antigen can be enhanced or otherwise improved in vitro, by isolating animal cells from a subject, “pulsing” or contacting them with the antigen, then using the pulsed cells to stimulate autologous T cells in vitro or in vivo.

The compositions of matter according to the invention could also be prepared to treat immunocompromised animals that may be suffering or have a propensity to suffer from bacterial, viral or yeast infection, protozoan or other parasite infection or have a cancer such as melanoma or other sarcoma or tumour.

From the foregoing, the invention broadly resides in a composition of matter comprising an immunostimulatory molecule and animal cells cultured in the presence of at least one interferon for a time and under conditions sufficient to enhance the antigen presenting function of said cells, wherein said cells have been washed to remove said interferon(s).

In a preferred embodiment, the present invention provides a composition of matter comprising animal cells which express an immunostimulatory membrane protein, and which have been cultured in the presence of IFN-gamma and one or both of IFN-alpha and IFN-beta for a time and under conditions sufficient to enhance the antigen presenting function of said cells, wherein said cells have been washed to remove said IFNs.

The treated cells in combination with the immunostimulatory molecule above can be used as actives for the treatment or prophylaxis of various conditions as, for example, a tumour or cancer. These therapeutic agents can be administered to a patient either by themselves or in vaccines where they are mixed with one or more pharmaceutically acceptable carriers, adjuvants and/or diluents.

4. Vaccines

The invention also contemplates a vaccine for stimulating a host's immune system, comprising a composition of animal cells as broadly described above, said vaccine optionally further comprising one or more pharmaceutically acceptable carriers, adjuvants and/or diluents.

Cultured animal cells in combination with an immunostimulatory molecule according to the invention may be used as actives in the preparation of vaccines. Such preparation uses routine methods known to persons skilled in the art. Typically, such vaccines are prepared as injectables, either as liquid solutions or suspensions; solid forms suitable for solution in, or suspension in, liquid prior to injection may also be prepared. The preparation may also be emulsified. The active immunogenic ingredients are often mixed with excipients that are pharmaceutically acceptable and compatible with the active ingredient. Suitable excipients are, for example, water, saline, dextrose, glycerol, ethanol, or the like and combinations thereof In addition, if desired, the vaccine may contain minor amounts of auxiliary substances such as wetting or emulsifying agents, pH buffering agents, and/or adjuvants that enhance the effectiveness of the vaccine. Examples of adjuvants which may be effective include but are not limited to: aluminium hydroxide, N-acetyl-muramyl-L-threonyly-D-isoglutamine (thur-MDP), N-acetyl-nor-muramyl-L-alanyl-D-isoglutamine (CGP 11637, referred to as nor-MDP), N-acetylmuramyl-L-alanyl-D-isoglutaminyl-L-alanine-2-(1′-2′-dipalmitoyl-sn-glycero-3-hydroxyphosphoryloxy)-ethylamine (CGP 1 983A, referred to as MTP-PE), and RIBI, which contains three components extracted from bacteria, monophosphoryl lipid A, trehalose dimycolate and cell wall skeleton (MPL+TDM+CWS) in a 2% squalene/Tween 80 emulsion. For example, the effectiveness of an adjuvant may be determined by measuring the amount of antibodies resulting from the administration of the vaccine, wherein those antibodies are directed against one or more antigens presented by the treated cells of the vaccine.

The cells should be administered in a pharmaceutically acceptable carrier, which is non-toxic to the cells and the individual. Such carrier may be the growth medium in which the cells were grown. Compatible excipients include isotonic saline, with or without a physiologically compatible buffer like phosphate or Hepes and nutrients such as dextrose, physiologically compatible ions, or amino acids, and various culture media suitable for use with cell populations, particularly those devoid of other immunogenic components. Carrying reagents, such as albumin and blood plasma fractions and nonactive thickening agents, may also be used. Non-active biological components, to the extent that they are present in the vaccine, are preferably derived from a syngeneic animal or human as that to be treated, and are even more preferably obtained previously from the subject. The injection site may be subcutaneous, intraperitoneal, intramuscular, intradermal, or intravenous.

If a soluble immunostimulatory molecule is employed as an active in the vaccine, the immunostimulatory molecule can be formulated into the vaccine as neutral or salt forms. Pharmaceutically acceptable salts include the acid addition salts (formed with free amino groups of the peptide) and which are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids such as acetic, oxalic, tartaric, maleic, and the like. Salts formed with the free carboxyl groups may also be derived from inorganic basis such as, for example, sodium, potassium, ammonium, calcium, or ferric hydroxides, and such organic basis as isopropylamine, trimethylamine, 2-ethylamino ethanol, histidine, procaine, and the like.

If desired, devices or compositions containing the vaccine and suitable for sustained or intermittent release could be, in effect, implanted in the body or topically applied thereto for the relatively slow release of such materials into the body.

It will be appreciated that the soluble immunostimulatory molecule may be administered to a patient separately to the administration of the cell-containing composition. Depending on the specific conditions being treated, the immunostimulatory molecule may be formulated and administered systemically or locally. Techniques for formulation and administration may be found in “Remington's Pharmaceutical Sciences,” Mack Publishing Co., Easton, Pa., latest edition. Suitable routes may, for example, include oral, rectal, transmucosal, or intestinal administration; parenteral delivery, including intramuscular, subcutaneous, intramedullary injections, as well as intrathecal, direct intraventricular, intravenous, intraperitoneal, intranasal, or intraocular injections.

The number of IFN-treated cells and optionally the quantity of the immunostimulatory molecule to be administered may depend on the subject to be treated inclusive of the age, sex, weight and general health condition thereof. In this regard, precise amounts of the agent(s) for administration will depend on the judgement of the practitioner. In determining the effective amount of the agent(s) to be administered in the treatment of a disease or condition, the physician may evaluate the progression of the disease or condition over time. In any event, those of skill in the art may readily determine suitable dosages of the agents of the invention without undue experimentation. Cell-containing compositions and vaccines are suitably administered to a patient in the range of between about 10⁴ and 10¹⁰, and more preferably between about 10⁶ and 10⁸ treated cells/administration. The dosage of the immunostimulatory molecule administered to a patient should be sufficient in combination with the cellular component of the vaccine to effect a beneficial response in the patient over time such as a reduction in the symptoms associated with the cancer or tumour. Dosage amount and interval may be adjusted individually to provide plasma levels of the immunostimulatory molecule which are sufficient to maintain immunostimulatory effects. Usual patient dosages for systemic administration range from 1-2000 mg/day, commonly from 1-250 mg/day, and typically from 10-150 mg/day. Stated in terms of patient body weight, usual dosages range from 0.02-25 mg/kg/day, commonly from 0.02-3 mg/kg/day, typically from 0.2-1.5 mg/kg/day.

Also encapsulated by the present invention is a method for treatment and/or prophylaxis of a disease or condition, comprising administering to a patient in need of such treatment a therapeutically effective amount of a composition or vaccine as broadly described above.

In one embodiment, the cell-containing composition or vaccine of the invention could also be used for generating large numbers of CD8⁺ or CD4+ CTL, for adoptive transfer to immunosuppressed individuals who are unable to mount normal immune responses. For example, antigen-specific CD8⁺ CTL can be adoptively transferred for therapeutic purposes in individuals afflicted with HIV infection (Koup et al., 1991, J. Exp. Med. 174: 1593-1600; Carmichael et al., 1993, J. Exp. Med. 177: 249-256; and Johnson et al., 1992, J. Exp. Med. 175: 961-971), malaria (Hill et al., 1992, Nature 360: 434-439) and malignant tumours such as melanoma (Van der Brogen et al., 1991, Science 254: 1643-1647; and Young and Steinman 1990, J. Exp. Med., 171: 1315-1332).

In another embodiment, the cell-containing composition or vaccine is suitable for treatment or prophylaxis of a cancer or tumour. Cancers or tumours which could be suitably treated in accordance with the practices of this invention include cancers or tumours of the lung such as small and large cell adenocarcinomas, squamous cell carcinoma, and brionchoalveolar carcinoma; breast tumours, such as ductal and lobular adenocarcinoma; gynecologic tumours, such as squamous and adenocarcinoma of the uterine cervix, and uterine and ovarian epithelial adenocarcinomaovary; colon tumours, such as epithelial adenocarcinoma and their metastases; pancreatic tumours such as pancreatic ductal adenocarcinomas; prostate tumours, such as prostatic adenocarcinoma; stomach; bladder tumours, such as transitional squamous cell carcinoma; kidney, bone, liver tumours, such as hepatoma and cholangiocarcinoma; tumours of the reticuloendothelial (RES) system, such as nodular or diffuse B or T cell lymphoma; plasmacytoma, and acute or chronic leukemia; oesophageal cancer; brain tumours, such as astrocytoma, oligodendroglioma, ependymoma, medulloblastomas, primitive neural ectodermal tumour, gliomas, glioblastomas, and gliosarcomas; testicular tumours; skin tumours, such as malignant melanoma; soft tissue tumours, such as soft tissue sarcoma and leiomyosarcoma; and the various leukemias and lymphomas. In a preferred embodiment, the cancer is melanoma or breast cancer.

In yet another embodiment, the cell-containing composition or vaccine is suitable for treatment or prophylaxis of a viral, bacterial or parasitic infection. Viral infections contemplated by the present invention include, but are not restricted to, infections caused by HIV, Hepatitis, Influenza, Japanese encephalitis virus, Epstein-Barr virus and respiratory syncytial virus. Bacterial infections include, but are not restricted to, those caused by Neisseria species, Meningococcal species, Haemophilus species Salmonella species, Streptococcal species, Legionella species and Mycobacterium species. Parasitic infections encompassed by the invention include, but are not restricted to, those caused by Plasmodium species, Schistosoma species, Leishmania species, Trypanosoma species, Toxoplasma species and Giardia species.

The effectiveness of the immunization may be assessed using any suitable technique. For example, CTL lysis assays may be employed using stimulated splenocytes or peripheral blood mononuclear cells (PBMC) on peptide coated or recombinant virus infected cells using ⁵¹Cr or Alamar Blue™ labeled target cells. Such assays can be performed using for example primate, mouse or human cells (Allen et al., 2000, J. Immunol. 164(9): 4968-4978 also Woodberry et al. infra). Alternatively, the efficacy of the immunization may be monitored using one or more techniques including, but not limited to, HLA class I tetramer staining—of both fresh and stimulated PBMCs (see for example Allen et al., supra), proliferation assays (Allen et al., supra), ELISPOT assays and intracellular IFN-gamma staining (Allen et al., supra), ELISA Assays—for linear B cell responses; and Western blots of cell sample expressing the synthetic polynucleotides

5. Process for Assessing Cellular Responsiveness to Interferon Treatment

The invention also extends to a process for assessing the responsiveness of animal cells to treatment with at least one interferon. The process comprises detecting in animal cells: (1) the level and/or functional activity of a polypeptide involved in interferon signalling; (2) the level and/or functional activity of a cellular modulatory agent that modulates said polypeptide; (3) the level and/or functional activity of a downstream cellular target of said polypeptide; or (4) the level of an expression product of a genetic sequence encoding a member selected from the group consisting of said polypeptide, said modulatory agent and said downstream cellular target.

Suitably, the polypeptide is selected from the group consisting of Stat1, IRF-1, Stat2 and p48 ISGF3. Preferably, the polypeptide is Stat1.

5.1 Detection of Polypeptides

Polypeptides, modulators and target polypeptides as mentioned above may be detected by contacting a sample of the animal cells or extract thereof with an antigen-binding molecule that is immuno-interactive with the polypeptide, modulator or target polypeptide and detecting the presence of a complex comprising the said antigen-binding molecule and the said polypeptide, modulator or target in said contacted sample.

Any suitable technique for determining formation of the complex may be used. For example, an antigen-binding molecule according to the invention, having a reporter molecule associated therewith may be utilised in immunoassays. Such immunoassays include, but are not limited to, radioimmunoassays (RIAs), enzyme-linked immunosorbent assays (ELISAs) and immunochromatographic techniques (ICTs), Western blotting which are well known to those of skill in the art. For example, reference may be made to Coligan et al., CURRENT PROTOCOLS IN IMMUNOLOGY, (John Wiley & Sons, Inc, 1994), which discloses a variety of immunoassays that may be used in accordance with the present invention. Immunoassays may include competitive assays as understood in the art or as for example described infra. It will be understood that the present invention encompasses qualitative and quantitative immunoassays.

Suitable immunoassay techniques are described for example in U.S. Pat. Nos. 4,016,043, 4,424,279 and 4,018,653. These include both single-site and two-site assays of the non-competitive types, as well as the traditional competitive binding assays. These assays also include direct binding of a labelled antigen-binding molecule to a target antigen.

Two site assays are particularly favoured for use in the present invention. A number of variations of these assays exist, all of which are intended to be encompassed by the present invention. Briefly, in a typical forward assay, an unlabelled antigen-binding molecule such as an unlabelled antibody is immobilised on a solid substrate and the sample to be tested brought into contact with the bound molecule. After a suitable period of incubation, for a period of time sufficient to allow formation of an antibody-antigen complex, another antigen-binding molecule, suitably a second antibody specific to the antigen, labelled with a reporter molecule capable of producing a detectable signal is then added and incubated, allowing time sufficient for the formation of another complex of antibody-antigen-labelled antibody. Any unreacted material is washed away and the presence of the antigen is determined by observation of a signal produced by the reporter molecule. The results may be either qualitative, by simple observation of the visible signal, or may be quantitated by comparing with a control sample containing known amounts of antigen. Variations on the forward assay include a simultaneous assay, in which both sample and labelled antibody are added simultaneously to the bound antibody. These techniques are well known to those skilled in the art, including minor variations as will be readily apparent. In accordance with the present invention, the sample is one that might contain an antigen including serum, whole blood, and plasma or lymph fluid. The sample is, therefore, generally a circulatory sample comprising circulatory fluid.

In the typical forward assay, a first antibody having specificity for the antigen or antigenic parts thereof is either covalently or passively bound to a solid surface. The solid surface is typically glass or a polymer, the most commonly used polymers being cellulose, polyacrylamide, nylon, polystyrene, polyvinyl chloride or polypropylene. The solid supports may be in the form of tubes, beads, discs of microplates, or any other surface suitable for conducting an immunoassay. The binding processes are well known in the art and generally consist of cross-linking covalently binding or physically adsorbing, the polymer-antibody complex is washed in preparation for the test sample. An aliquot of the sample to be tested is then added to the solid phase complex and incubated for a period of time sufficient and under suitable conditions to allow binding of any antigen present to the antibody. Following the incubation period, the antigen-antibody complex is washed and dried and incubated with a second antibody specific for a portion of the antigen. The second antibody has generally a reporter molecule associated therewith that is used to indicate the binding of the second antibody to the antigen. The amount of labelled antibody that binds, as determined by the associated reporter molecule, is proportional to the amount of antigen bound to the immobilised first antibody.

An alternative method involves immobilising the antigen in the biological sample and then exposing the immobilised antigen to specific antibody that may or may not be labelled with a reporter molecule. Depending on the amount of target and the strength of the reporter molecule signal, a bound antigen may be detectable by direct labelling with the antibody. Alternatively, a second labelled antibody, specific to the first antibody is exposed to the target-first antibody complex to form a target-first antibody-second antibody tertiary complex. The complex is detected by the signal emitted by the reporter molecule.

In a preferred embodiment, the polypeptides, modulators and target polypeptides as broadly described above may be detected, quantified or semi-quantified by flow cytometric analysis and immunofluorescent staining of intracellular antigens with antibodies to quantify and compare individual cells for antigen expression levels as for example disclosed by Clevenger, et al (1987, J. Cell Physiol. 130: 336-343) and by Kuhar and Lehman (1991, Oncogene 6: 1499-1506).

In an alternate embodiment, detection, quantification and semi-quantification may be effected using immunohistological analysis (e.g. diaminobenzidine staining of thin sections) as is known in the art.

From the foregoing, it will be appreciated that the reporter molecule associated with the antigen-binding molecule may include the following:

-   -   (a) direct attachment of the reporter molecule to the         antigen-binding molecule;     -   (b) indirect attachment of the reporter molecule to the         antigen-binding molecule; i.e., attachment of the reporter         molecule to another assay reagent which subsequently binds to         the antigen-binding molecule; and     -   (c) attachment to a subsequent reaction product of the         antigen-binding molecule.

The reporter molecule may be selected from a group including a chromogen, a catalyst, an enzyme, a fluorochrome, a chemiluminescent molecule, a lanthanide ion such as Europium (Eu³⁴), a radioisotope and a direct visual label.

In the case of a direct visual label, use may be made of a colloidal metallic or non-metallic particle, a dye particle, an enzyme or a substrate, an organic polymer, a latex particle, a liposome, or other vesicle containing a signal producing substance and the like.

A large number of enzymes suitable for use as reporter molecules is disclosed in U.S. Patent Specifications U.S. Pat. Nos. 4,366,241, 4,843,000, and 4,849,338. Suitable enzymes useful in the present invention include alkaline phosphatase, horseradish peroxidase, luciferase, β-galactosidase, glucose oxidase, lysozyme, malate dehydrogenase and the like. The enzymes may be used alone or in combination with a second enzyme that is in solution.

Suitable fluorochromes include, but are not limited to, fluorescein isothiocyanate (FITC), tetramethylrhodamine isothiocyanate (TRITC), R-Phycoerythrin (RPE), and Texas Red. Other exemplary fluorochromes include those discussed by Dower et al. (International Publication WO 93/06121). Reference also may be made to the fluorochromes described in U.S. Pat. No. 5,573,909 (Singer et al), U.S. Pat. No. 5,326,692 (Brinkley et al). Alternatively, reference may be made to the fluorochromes described in U.S. Pat. Nos. 5,227,487, 5,274,113, 5,405,975, 5,433,896, 5,442,045, 5,451,663, 5,453,517, 5,459,276, 5,516,864, 5,648,270 and 5,723,218.

In the case of an enzyme immunoassay, an enzyme is conjugated to the second antibody, generally by means of glutaraldehyde or periodate. As will be readily recognised, however, a wide variety of different conjugation techniques exist which are readily available to the skilled artisan. The substrates to be used with the specific enzymes are generally chosen for the production of, upon hydrolysis by the corresponding enzyme, a detectable colour change. Examples of suitable enzymes include those described supra. It is also possible to employ fluorogenic substrates, which yield a fluorescent product rather than the chromogenic substrates noted above. In all cases, the enzyme-labelled antibody is added to the first antibody-antigen complex. It is then allowed to bind, and excess reagent is washed away. A solution containing the appropriate substrate is then added to the complex of antibody-antigen-antibody. The substrate will react with the enzyme linked to the second antibody, giving a qualitative visual signal, which may be further quantitated, usually spectrophotometrically, to give an indication of the amount of antigen which was present in the sample.

Alternately, fluorescent compounds, such as fluorescein, rhodamine and the lanthanide, europium (EU), may be chemically coupled to antibodies without altering their binding capacity. When activated by illumination with light of a particular wavelength, the fluorochrome-labelled antibody adsorbs the light energy, inducing a state to excitability in the molecule, followed by emission of the light at a characteristic colour visually detectable with a light microscope. The fluorescent-labelled antibody is allowed to bind to the first antibody-antigen complex. After washing off the unbound reagent, the remaining tertiary complex is then exposed to light of an appropriate wavelength. The fluorescence observed indicates the presence of the antigen of interest. Immunofluorometric assays (IFMA) are well established in the art. However, other reporter molecules, such as radioisotope, chemiluminescent or bioluminescent molecules may also be employed.

5.2 Detection of Polynucleotides

In another embodiment, the method for detection comprises detecting expression in animal cells, or in extracts thereof, the level of an expression product of a genetic sequence encoding a member selected from the group consisting of said polypeptide, said modulatory agent and said downstream cellular target. Expression of the a polynucleotide may be determined using any suitable technique. For example, a labelled polynucleotide encoding a said member may be utilised as a probe in a Northern blot of a RNA extract obtained from the muscle cell. Preferably, a nucleic acid extract from the animal is utilised in concert with oligonucleotide primers corresponding to sense and antisense sequences of a polynucleotide encoding a said member, or flanking sequences thereof, in a nucleic acid amplification reaction such as RT PCR. A variety of automated solid-phase detection techniques are also appropriate. For example, very large scale immobilised primer arrays (VLSIPS™) are used for the detection of nucleic acids as for example described by Fodor et al., (1991, Science 251:767-777) and Kazal et al., (1996, Nature Medicine 2:753-759). The above generic techniques are well known to persons skilled in the art.

6. Methods for Assessing Cytotoxic T Lymphocyte Activity

The cytotoxic activity of T lymphocytes may be assessed by any suitable technique known to those of skill in the art. For example, a sample comprising T lymphocytes to be assayed for cytotoxic activity is obtained and the T lymphocytes are then exposed to IFN-treated target cells according to the invention. After an appropriate period of time, which may be determined by assessing the cytotoxic activity of a control population of T lymphocytes which are known to be capable of being induced to become cytotoxic cells, the T lymphocytes to be assessed are tested for cytotoxic activity in a standard cytotoxic assay. Such assays may include, but are not limited to, the chromium release CTL assay and the Alamar Blue™ fluorescence assay known in the art.

The method of assessing CTL activity is particularly useful for evaluating an individual's capacity to generate a cytotoxic response against cells expressing tumour or antigens of a pathogenic organism (e.g., viral antigens). Accordingly, this method is useful for evaluating an individual's ability to mount an immune response against a cancer or a pathogenic organism.

The invention also contemplates the use of IFN treatment in accordance with the teachings of the present invention to enhance the sensitivity of detecting cytolytic T lymphocyte (CTL) mediated lysis of a target cell. Accordingly, IFN treatment of a target cell can be used advantageously to develop assays with improved sensitivity for detecting an immune response, particularly a CTL response, and more particularly a CD8⁺ CTL response, against that target cell.

In order that the invention may be readily understood and put into practical effect, particular preferred embodiments will now be described by way of the following non-limiting examples.

EXAMPLES Example 1

Cell Cultures in IFN Stimulation

Melanoma cell line B16 (American type Culture Collection, Rockville, Md., USA), alone or transduced with a vector expressing murine B7-1 (polynucleotide encoding murine B7-1 cloned into pEF-MC1Neo-pA using PCR based methods), was grown in RPMI 1640 media supplemented with 10% v/v inactivated foetal calf serum (FCS), L-glutamine and sodium pyruvate at 37° C. in a 5% v/v CO₂ incubator. In all experiments, cells were maintained in serum free media (without 10% v/v FCS) for 24 h before stimulation with IFN. In those experiments using gamma-priming, cells were pre-treated with 1000 IU/nL IFN-gamma (Amersham, Sydney, New South Wales, Australia) for 16-18 h at 37° C. in 5% v/v CO₂ incubator prior to stimulation with 1000 IU/mL IFN-alpha2a (Hoffman-La Roche, Basel, Switzerland) for the indicated time periods.

Recombinant IFNs were used throughout the study. Murine IFN-beta was obtained from Toray Industries, Inc., Kanagawa, Japan. Murine IFN-gamma was produced in the laboratory using the pPR-TGATG-1 vector system in E. coli strain DH5α (43) and was isolated from inclusion bodies, denatured in 6M Guanidinium HCl, refolded by slow dialysis, clarified and purified by ion-exchange chromatography on S-Sepharose Fast Flow (Pharmacia). The biological activity of IFNs in IU/mL was calibrated against NIH IFN-alpha and -beta reference standards (IPN-beta #Gb02-902-511, IFN-alpha #Ga02-901 -511 obtained from the National Institute of Allergy and Infections Diseases, Bethesda, Md.) using an antiviral bioassay based on the inhibition of cytopathic effect of Semliki Forest virus in MDBK cells, similar to that described in (44).

Example 2

Cytotoxic T Cell Assay

Chromium Release Assay

A four hour ⁵¹Cr release Cytotoxic T Cell assay was carried out using the B16 mouse melanoma cell line as targets or alternatively, transfected B16 cells expressing B7-1. The targets were set up at a sub-confluent state, 60 hrs before the CTL assay. Within 12 hrs of setting up the cells in culture (in Dulbecco's Modified Eagles medium, 10% FCS, 50 U/mL Penicillin, 50 μg/nL Streptomycin), Murine Interferon gamma at 1000 IU/mL was added, followed by an addition of Murine Interferon beta at 1000 IU/mL 24hrs later.

A standard Chromium release assay was carried out where the targets were labelled with 150 μCi/mL Na₂ ⁵¹CrO₄ for 60-90 min and used to incubate with cultured splenocytes for 4 hrs at 37° C., 5% CO₂. CTL lysis was determined at effector:target (E:T) ratios ranging from 100:1 to 0.4:1. Supernatants (50 μL/sample) were harvested and counted using a scintillation cocktail (200 μL/sample well) (Star Scint, Canberra Packard) in a Top Count (Canberra Packard) using a 96 well plate format. Supernatants were also counted directly using a Gamma Counter (Canberra Packard). percent Specific Lysis was calculated using the following formula:

${\%\mspace{14mu}{Specific}\mspace{14mu}{Lysis}} = {100 \times \frac{\left( {{{experimental}\mspace{14mu}{release}} - {{spontaneous}\mspace{14mu}{release}}} \right)\;}{\left( {{{maximum}\mspace{14mu}{release}} - {{spontaneous}\mspace{14mu}{release}}} \right)}}$

Maximum release of the targets was determined by lysis with 1% NP-40. In a CTL assay where spontaneously released values (cpm) were in excess of 20% of the maximum release, the assay was discarded.

Fluorescence Based CTL Assay

For the cytotoxicity assay using Alamar Blue™ (BioSource International, Camarillo, Calif., USA), the methods of Nociari et al., 1998 (42) were, followed. Thus, 1×10³ target cells were seeded per well and effector:target ratios (E:T) of 30:1, 25:1, 20:1, 15:1, 10:1, 7.5:1, 5:1, 2.5:1, 1.25:1, 0.625:1, 0.3125:1, 0.156:1 and 0.078:1 were used, as required. Each E:T ratio was performed in quadruplicate wells. Alamar Blue™ stock solution was added to the wells at time 0 after setting up the CTL assay at a final concentration of 10% and the plate was incubated at 37° C. in a humidified CO₂ incubator and read at 24 h The fluorescence signal generated in each well was determined using an excitation wavelength of 520-530 nm and the emission at 590-595 nm. Fluorescence units detected for Targets alone and Effectors alone were correlated with values for the E:T mixed wells.

The cell lysis was calculated using the following equation:

${\%\mspace{14mu}{Lysis}} = {100 \times \frac{\begin{matrix} \left\{ {\left( {{AF}^{*}\mspace{14mu}{Targets}\mspace{14mu}{Alone}} \right) +} \right. \\ {\left. \left( {{AF}\mspace{14mu}{Effectors}\mspace{14mu}{Alone}} \right) \right\} - \left\{ \left( {{AF}\mspace{14mu} E\text{:}T\mspace{14mu}{mixture}} \right\} \right)} \end{matrix}}{\left. \left( {{AF}\mspace{14mu}{Targets}\mspace{14mu}{Alone}} \right) \right\}}}$  ^(*)AF  represents  the  mean  of  the  absolute  fluorescence  units  of Targets  alone, or  Effectors  alone,  or  E:T  mixture,  minus  the  average fluorescence  units  of  the  media  plus  dye  controls.

Example 3

Preparation of Splenocytes for CTL Assays:

C57B7/6J male mice were subjected to an immunisation regime, 13 days prior the CTL assay. The mice were injected in the intra peritoneal cavity with irradiated 10⁷ B16 cells or B16-B7.1 cells. The cell preparations used as vaccine were pre-treated with interferon gamma for 72 h and murine interferon beta for 48 h prior to use. Six days after injection of immunogen, splenic lymphocytes were prepared. Red blood cells were lysed with 0.83% ammonium chloride solution buffered in Tris, pH 7.2 at 37° C., 2 mins. Splenic lymphocytes were plated out into 24 well plates at 4×10⁶ cells/well in RPMI-1640 (Sigma) supplemented with 10% FCS (Commonwealth Serum Lab), 50 U/mL Penicillin (Trace Scientific Ltd), 50 μg/mL Streptomycin (Trace Scientific Ltd), 1.66 mM L-Glutamate (Sigma), 2 mM Sodium Pyruvate (Sigma), 20 mM Hepes (Sigma), 50 μM 2-mercaptoethanol (ICN).

To the splenic lymphocytes in culture, 2×10⁵ irradiated stimulator cells/well were added and incubated at 37° C., 5% CO₂. Stimulators comprised of B16 cells or B16-B7.1 cells, which were pre treated with murine interferon gamma for 72 h and murine interferon beta for 48 h.

Two days before the CTL assay, the mixed lymphocyte culture (MLC)/stimulator medium was replenished with fresh medium.

On the day of the CTL assay, the MLC/stimulators were pooled and resuspended in a small volume and layered onto a cushion of Ficoll-Paque (Sigma). CTLs were collected from the interface between the cushion and the growth medium after centrifuging at 1200 rpm, 20 min. CTLs were washed in PBS and resuspended at 3-6×10⁷ cells/mL were then ready to be plated out at Effector:Target ratios of 100:1-0.4:1.

Example 4

Immunofluorescence Cytometry:

After IFN treatment, cells (3×10⁵) were incubated with an appropriate dilution (1×PBS containing 0.5% v/v FCS) of anti-monomorphic MHC Class I antiserum for 1 h on ice. After washing three times with 1×PBS/0.5% v/v FCS, anti-mouse FITC-conjugated antiserum (Silenus) was added and incubated for an additional 1 h on ice. The cells were again washed three times and incubated in fixative solution (1% v/v formaldehyde, 0.03% NaN₃ and 1 g/50 mL glucose) overnight and then analysed by flow cytometry using a Becton Dickinson FACS IV gated.

The methods used for analysing cells by immunofluorescence scanning on a FACSCalibur™ (Becton-Dickinson, Mountain View, Calif.) have been previously described. (see Wong et al., J. Immunol. 1998, 160: 5475-5484). Antibodies used were: Rat IgG2a, anti-murine B7-1 monoclonal antibody 1G10, Phycoerythrin conjugated (Pharmingen, San Diego, Calif.); IgG2a, YN1/17.4 Rat anti-murine ICAM-1 monoclonal antibody (ATCC CRL1879, American Type Culture Collection, Rockville, Md.); Mouse anti-murine MHC H-2 K^(b)D^(b) monoclonal antibody, ASH 1474 kindly supplied by Professor Ian MacKenzie, Austin Research Institute, Heidelberg, Melbourne).

Example 5

CD4/CD8 CTL Purification:

Dynabead kits were used to separate and purify the different CD8+ and CD4+ CTL populations according to the manufacturer's instructions (Dynal Pty Ltd, Carlton South, Victoria, Australia).

Example 6

Interferon Treatment Significantly Increases Cell Surface Levels of the CTL Reactive Receptor Molecules

The B16 murine melanoma model is a close facsimile of advanced stage malignant melanoma in humans. As it was shown for human melanoma cell lines, treatment of the wild type B16 F10 cell line with either types of interferon resulted in significant increases in the levels of expression of MHC Class I antigens on the cell surface. Also, again as with the human melanoma cell lines, interferon gamma/beta treatment was found to consistently provide the highest increase in the expression of surface MHC class I molecules on the murine B16 melanoma cells. An example of the interferon-mediated increase in MHC class I immunofluorescence scanning profile of the stained cells in presented is FIG. 2. Note that B16 cells, in the absence of interferon treatment, exhibit low levels of MHC class I expression above non-specific background fluorescence. Large increases in expression of MHC class I were reproducibly obtained when cells were first primed with 1000 IU/mL-interferon gamma before treatment with interferon alpha (1000 IU/mL) for a further period. Typical results of a time course of induction by interferons and the relative increases in MHC Class I expression are presented in Table 1. It can be seen that the increases in MHC class I expression levels often were up to 100 times greater than that of control non-treated cell populations. Treatment with interferon gamma 72 h/beta48 h was selected as optimal because this treatment commonly produced the highest levels of class I expression and the levels then declined after long periods of interferon treatment.

Example 7

Interferon Treatment has a Small Effect on B7-1 or ICAM-1 Expression on B16 Cells

The co-stimulatory molecule, B7-1 has been discussed above and shown to play a key Tole in stimulating activation and proliferation of CTLs. In the absence of B7-1 expression, CD3 activation results in death and subsequent loss of killer T cell function (32). B7-1 binds to the surface receptor, CD28 (33, 34, 35) and the combined signal of MHC class I with CD3 and B7-1 with CD28 drives the proliferative response expanding the representative clones of reactive CTLs. Levels of the B7-1 antigen and another molecule on B16, ICAM-1, also involved in T cell-cancer cell binding interactions were not greatly increased by treatment with interferon (FIG. 3). Occasionally, marginal increases (24 times control levels) in expression of B7-1 and ICAM-1 were detected but these were not routinely reproducible and at other times, no significant increase was found (Table 2a,b respectively). Others have also shown that B16 cells express low to undetectable levels of ICAM-1 or B7-2 (36,37,38). For this reason, and because the absence of B7 causes T cell loss, B 16 cell lines were produced which expressed increased levels of B7-1 antigen.

Example 8

Production of Transfected B16 Cell Lines Expressing Increased Levels of B7-1

The wild type B16-F10 cells deficient in B7 expression were found to be poor producers of CTL immune responses (see below). Therefore, sub-lines of B16-F10 cells were derived by transfection expressing high levels of B7 antigen. These lines were selected to constitutively express higher levels of B7-1 relative to wild type B16 cells. Two clonally derived B16-F10 cell lines transfected to express different levels of B-7 were produced and further investigated. Clone B7-1Med (with medium1 B7-1 expression levels) and B7-1Hi (with high expression were analysed by immunofluorescence scanning before and after interferon treatment (results presented in FIG. 4).

Example 9

Increased Levels of Expression of MHC Class 1, B7-1 and ICAM-1 on B16 Cells Transfected with Murine B7-1 Antigen and Treated with Interferons

The levels of B7-1 expression on these cloned lines remained unaffected by the different treatments of these cells with interferons. In addition, both of the B7-1 positive (B7+) cell lines generally retained their response to interferon treatment despite having been transfected. Similar increased levels of MHC Class I resulted after interferon treatment as before, but no significant increases in ICAM-1 were detected compared with the slight increase produced on wild type B16-F10 cells after optimal induction with interferons (FIG. 5).

Example 10

Treating Target Cells with Interferons Greatly Increases the Extent of Cytotoxic Lysis

Detection of cell lysis in cytotoxic assays depends on the ability to induce adequate production of immune effector cells in mixed lymphocyte cultures (MLC) which include cytotoxic T lymphocytes, large granular lymphocytes or natural killer cells. These effector cells can then be assayed by their ability to lyse target cells loaded with an appropriate indicator such as 51-Chromium, luciferase or other molecules allowing detecting of membrane disruption or compromised target cell viability. The cytolytic reaction requires the effector cell to recognise and bind to the target cell via a series of coordinated complex interactions on the opposing cell surfaces that result in activation of the killing response. The low levels of immune cell populations resulting after in vivo immunisation are often insufficient to allow their immediate detecting in most in vitro assays. Thus, an interim preparatory step is required whereby population numbers of cytotoxic effector cells must first be amplified before assay in order that they are detected. This interim procedure commonly involves culturing cytotoxic immune effector cells derived from the host source in the presence of irradiated feeder/stimulator cells. Co-cultures also often include additional factors such as the cytokine interleukin-2 (IL-2) and antigen for the purpose of helping to expand the effector cell numbers by growth stimulation over a period of several days in culture.

During the procedure for assaying immunised mice for levels of cytotoxic responses, splenic lymphocytes are commonly harvested from the mice and then plated out into culture dishes together with irradiated feeder/stimulator cells. These cultures are incubated for about one week, often containing supplemented IL-2 and serve the purpose of inducing growth and increased numbers of immune cells to facilitate detecting of the cytotoxic effector cells. The inventors analysed the effects of pretreating cancer cells with interferons on the production of effector anti-cancer immune cells by using in vitro cytotoxicity assays. Thus, wild type B16 cells treated or not with interferons were compared by assaying their effects when used either as

-   immunogens (single injection into mice), or as -   stimulators added to MLC from injected mice (syngeneic or     allogeneic) or as -   51-Chromium-loaded target cells.

All cancer cell preparations used as stimulators were lethally irradiated before co-culture with the splenic derived effector populations in the absence of IL-2 as it was found that sufficient cytotoxic effector cell activity was produced without requiring additional IL-2.

Example 11

B7-1 Hi B16 Cells Produce Greater Immune Responses than the Wild Type B16 Cells

No significant anti-cancer immune cell activity was produced when the untreated wild type B16 melanoma cells were used as immunogen, stimulators and target cells as measured using the in vitro cytotoxicity assay (see FIG. 6). However, when the B7-1 highly expressing B 16 cells were used throughout, significant anti-cancer immune cell activity was measured with 30% lysis at an effector to target ratio of 12.5:1. This result confirmed that the expression of B7-1 was important to stimulate the production of immune effector cells.

Example 12

B7-1 Transfected B16 Cells Treated with Inteferons and Used as Stimulators and/or Target Cell Populations Produce Significant Immune Responses

A preparation of MLC from syngeneic mice immunised with interferon treated, B7-1 Hi B16 cells was divided into two portions. Each of these were amplified using either interferon treated B7-1Hi B16 cells (B7+, IFN+; FIG. 7) or wild type B16 stimulator cells not reacted with interferons (B37−, IFN−; FIG. 7). The immune responses were assayed using interferon treated wild type B16 cells as the targets for both MLC preparations. Use of the B7+, IFN+ stimulator cells resulted in a significant immune response above the level produced by B7−, IFN− stimulators. This result highlights the benefits obtained by using the interferon treatment of B7-1 positive cells in the immunopotentiating composition of the invention in order to produce an immune response against B7 negative cancer cell targets.

Example 13

Preparations Combining Interferon Treatment of B7 Positive Cells Provide Stronger Immune Cell Responses than Those Obtained Without Use of Interferon

The results from a comparison of B7-1Hi B16 cells treated or not with interferon and used as stimulators and targets is presented in FIG. 8A (B7+, IFN+ vs B7+, IFN). Thus, when the B7Hi stimulators and target cells are treated with interferon (B7+,IFN+), significantly enhanced efficiencies of target cell killing (FIG. 8B; 5 times more lytic units calculated using the quantitative method outlined in [24]) result compared to those obtained using B7Hi B16 cells without interferon treatment (B7+,IFN−). Thus, reduced immune response resulted when B7 positive stimulators and target cells were not treated with interferon. Up to 60-70% lysis of target cells occurred at effector: target ratios of only 12.5:1 when the B7 positive stimulators and targets were interferon treated first (see FIG. 8). These results clearly demonstrate the beneficial impact of the treatment with interferon in the generation of strong immune responses when B7 positive cancer cells are used in the immunopotentiating composition.

Example 14

Cytotoxic Responses are Predominantly the Result of CD8 Positive T Lymphocyte Killer Activity

Analysis of the type of immune effector cells which resulted from stimulation with the B16B7-1Hi interferon treated cells in MLC from syngeneic mice was carried out using Dynabeads™ and cell affinity purification with either IgG2a rat anti-murine CD4 (GK1.5, American Type Culture Collection TIB207, Rockville, Md.) or IgG anti-Cd8 (53-69.72, American Type Culture Collection TIB105, Rockville, Md.). The results presented in FIG. 9 revealed that the CD8 positive selected killer T cell population accounted for almost the entire immune effector cell species responsible for the anti-tumour cell cytolytic activity. No significant level of cytolytic activity was detected in the CD4 population. After affinity separation, no detectable cytolytic activity remained in the residual cell population either, indicating that all immune effector cells had been accounted for in the CD8 depleted population by this procedure.

Example 15

Expression of B7 on the Target Cancer Cells and their Treatment with Interferon is not Required to Obtain Efficient Killing

The present inventors have established that strong immune responses to modified cancer cells can be produced. A key issue regarding the proposed immunopotentiating composition as a form of therapy is whether those immune effector cells induced are capable of recognising and efficiently killing endogenous cancer cells in the animal which lack B7 expression and have not reacted with interferon. The inventors, therefore, determined the effects of B7 expression and interferon treatment on the recognition and killing of target cells measured using the cytotoxicity assay. Firstly, the effect of B7 expression on target cells was examined. The target populations used were either B7Hi interferon treated cells (B7+, IFN+ targets) or wild type B16 cells treated with interferon (B7−, IFN+). The interferon treated B7-1Hi vaccine was applied to syngeneic mice and interferon treated B7-1Hi stimulators (B7+, IFN+) were used and the MLC tested on the two different targets. The results are presented in FIG. 10. When wild type B16 (B7−,IFN+) cells were used as the targets, only 20% maximum lysis was obtained. However, a maximum lysis of 35% was obtained with interferon treated B16B7-1Med as targets. Quantitative comparison of relative lytic units [24] showed that B7 expression on the targets (B7+, IFN+) made them 3 times more susceptible to lysis than B7 negative cells (B7−, IFN+). Nevertheless, B7 negative target cells are efficiently lysed by the immune effector cells. When the targets tested were B16 wild type cells (B7−) treated or not with interferon (see FIG. 7), the results showed that B7-1 negative cancer cells not treated with interferon were still killed efficiently by MLC induced using the immunopotentiating composition. Comparing the relative lytic units for the interferon treated versus the untreated cancer cell targets, there was a 50% reduction in lytic efficiency against the target cells not treated with interferons B7−, IFN−. Thus, it can be concluded that even in situations where the cancer cells do not express B7 and have not been induced by interferon, they are still susceptible to efficient killing by immune cells induced using the immunopotentiating composition.

Example 16

Use of the Immunopotentiating Composition Produces Immune Responses in Syngeneic Mice Equivalent to those Obtained in Allogeneic Mice

Immune cell responses are often severe in graft versus host rejection because these responses are induced against backgrounds involving considerable genetic differences between the grafted and the host immune systems. Allogeneic responses are commonly used as the hallmark standard for immune reactions because the genetic differences involved are usually large enough to provoke a strong immune response which can then be readily detected. For these reasons, the immunopotentiating composition of the invention was purposely compared for its ability to provoke comparatively strong anti-cancer immune killer cell responses in both syngeneic and allogeneic systems. For the allogeneic system, the Balb/c white mouse strain was used, which is genetically defined at the MHC locus as H-2d as opposed to the H-2b of the C57Black6 mouse strain from which the B16 melanoma is derived.

FIG. 11 shows the results from analyses of CTL responses obtained when Balb/c mice were used as the allogeneic control system compared to the responses obtained in C57B16 syngeneic mice. In the control allogeneic assays, MLC from Balb/c mice provided efficient killing [plateau at ˜60% maximum lysis at effector:target ratio of 50:1 (7.9.98 FIG. 11)] of C57B16 splenocytes when they were used for both the stimulators and targets. When interferon treated B16 wild type cells (B7−IFN+) were substituted as the targets, allogeneic killing remained high, with results showing a similar profile in the lytic curve. However, no significant killing activity was detected when samples from the same allogeneic MLC population were assayed on the untreated B16 wild type target cells (B7−, IFN−, results not shown). Thus, interferon treatment also significantly improved allogeneic mediated cytotoxic lysis of wild type B16 target cells. Furthermore, interferon treated B16 wild type cells proved to be more effective targets than untreated B16 wild type cells in assays using either the allogeneic or syngeneic MLC, albeit that responses with syngeneic MLC were only detected at high effector:target ratios and resulted in much lower levels of cytolysis, <10% (FIG. 11). Much greater cytotoxic lysis was observed in all assays comparing interferon treated versus non-treated targets.

FIG. 12 shows an example of a comparative analysis of the immune responses obtained in allogeneic versus syngeneic mice injected with the B7Hi interferon treated B16 vaccine, and analysed after stimulation on B7Hi interferon treated B16 cells using B7Hi interferon treated target cells. It can be seen from the cytotoxicity assay that the resulting immune responses induced in the two genetically different systems are very similar, both producing strong lysis of the target cells. This is confirmed by comparative analysis of the relative lytic units produced by each. The result was determined as 10⁵ effector cells/1 Lytic Unit (30% lysis) for both preparations (see reference (39)). Thus, using the optimal immunopotentiating composition described, the levels of response induced in syngeneic mice approach those normally only produced using allogeneic systems.

Example 17

Preclinical Trials using the Immunopotentiating Composition as a Cancer Vaccine

Treatment of cells with gamma interferon for 72 h and beta interferon for 48 h was shown to optimally induce increased levels of surface expression of MIC class I on melanoma cells, particularly on human melanoma cells. Levels of ICAM-1 and B7 antigens on the human cells were also elevated by interferon treatment. However, given the common loss of B7 expression on these cells, the immunopotentiating composition includes transfection to express B7-1 antigen. The transfected B7 expressing murine melanoma cells were shown to be unaltered in their responses to the optimal interferon treatment showing similar strong inductions of MHC Class I antigen. Results from studies with the B16 melanoma model showed the expression of B7-1 and interferon treatment were important for producing CD8 positive CTLs with potent cytolytic activity against B16 cancer cells and that these cells were capable of lysing target cells even though they did not express B7 antigen. Given the level of immunity shown to be induced by the B7Hi interferon treated B16 cells measured by cytotoxicity assay, the same cell preparations were tested for their ability to induce anti-cancer immunity in whole animals when injected as a vaccine. The protocol compared the use of B7Hi/B16 transfected cells to vaccination with wild type B16 cells. The cells were irradiated and cohorts of mice were vaccinated by intraperitoneal injection weekly for up to six weeks. Vaccinated mice were challenged at week 7 with an injection subcutaneously on the rear flank with 5×10⁵ B7Med B16 cells. The results from this trial are presented in FIG. 13. All twenty control animals receiving only the challenge cancer cells succumbed to a 2 cm tumour growth by day 38. However, mice vaccinated with the B7Hi interferon treated immunopotentiating composition produced the greatest resistance to the challenge with 90% (18 out of 20 mice) surviving with no sign of tumour and continued to remain tumour free thereafter. The other trial cohorts showed different levels of immunity, with less successful outcomes [refer to FIG. 13 for details]. Thus, it can be concluded that the B7Hi/interferon treated immunopotentiating composition induced potent CD8 positive CTL responses and these were capable of providing sufficient immunity to protect the majority of vaccinated mice from the cancer cells.

Example 18

Heterogeneous Antigenic Vaccine

Either autologous or MHC matched allogeneic cells are chosen. The cells are propagated and maintained in culture. Populations of cells (1-2×10⁶/mL) are pre-treated with high levels of gamma-interferon (500-1000 IU/mL) for 16-24 h before challenge with high levels of Type I interferon (500-1000 IU/mL) for 24-48 h until maximal expression of MHC class I molecules including B-7 is detected. The cells are treated by, for example, irradiation or other suitable means to destroy replicative ability under conditions to be established for the particular cells. The cell preparation may include adjuvants such as ISCOMS (trademark) and bacterial products at therapeutic doses. The vaccines are then injected subcutaneously or intramuscularly. Successive doses of the vaccine are prepared fresh and injected weekly over several weeks until the cytotoxic T-cell response of the recipient to the non-interferon treated cells is significantly elevated.

Example 19

Targeted Antigenic Vaccine

Either autologous or MHC matched allogeneic cells are chosen. The cells are propagated and maintained in culture. Populations of cells (1-2×10⁶/mL) pre-treated with high levels of gamma interferon (500-1000 IU/mL) for 16-24 h before challenge with high levels of Type I interferon (500-1000 IU/mL) for 24-48 h until maximal expression of MHC class I molecules is detected. The cells are then subjected to acid elution of peptide epitopes from the MHC surface molecules using washing with cold acid buffers (0.131M citrate, 0.066M Na₂HPO4, pH 3.0) for 1 minute at 4° C. The cells are washed with cold PBS and then incubated in the presence of specific peptide antigens and beta-2-microglobulin. The cells are then treated, by, for example, irradiation or other suitable means to destroy replicative ability under conditions to be established for the particular cells. The cell preparation may include adjuvants such as ISCOMS™ and bacterial products at therapeutic doses. The vaccines are then injected subcutaneously or intramuscularly. Successive doses of the vaccine are prepared fresh and injected weekly over several weeks until the cytotoxic T-cell response of the recipient to the non-interferon treated cells is significantly elevated.

Example 20

Assessment of Responsiveness of Melanoma Cells to Interferon Treatment

The present inventors have established that deficient levels of Stat1 exist in IFN-resistant skin melanoma cells at low passage in culture. Immunofluorescence cytometry detects relative levels of Stat1 expression. This analysis provides a way of analysing samples of melanoma cells directly harvested and prepared from patients' tumours. Thus, cells from the melanoma lines are permeabilised and fixed as outlined in (38), before immunostaining with a specific murine IgG1 anti-Stat1 monoclonal antibody and detection using an FITC-conjugated affinity purified sheep-anti-mouse Ig secondary antibody. The samples are counterstained with a melanoma specific marker. The murine IgG2a chondroitin sulfate proteoglycan (MCSP) as a melanoma specific marker. Isotype matched control mouse Ig is used for control immunostaining of cell samples. Immunostained cell samples are analysed using an immunofluorescence cytometer, for example a FACSCalibur™ (Becton-Dickinson). The development of this technique provides improved specificity and sensitivity when determining the levels of Stat1 expression and their variation directly in the tumour cells extracted from the patient melanoma samples. This information is useful for determining whether potentially IFN resistant cancer cells exist in the patient's tumour samples in vivo. Direct samples of primary melanoma for this analysis either as 3 mm punch biopsies from anaesthetised skin or thin needle aspirates providing at least 10⁶-10⁷ melanoma cells per sample, is more than sufficient for the analyses. This assay provides information on responsiveness of melanoma cells to IFN in relation to the staging of development of melanoma and patient responses.

Example 21

B7-1 Transfected B16-F10 Cells Treated with IFNs as Target Cell Populations are More Highly Susceptible to CTL-Mediated Catotoxicity Analysed by In Vitro Assay.

Given the marked increase in tumour cell killing activity obtained in mice receiving the IFN-gamma/-beta treated B16-F10/B₇-1^(hi) cell vaccine (FIGS. 6-9), the effectors derived from these mice were analysed further. An assessment of the relative contributions of each of the modifications, B7-1 expression versus IFN treatment on the extent of killing was made. Thus, MLCs were compared for their ability to kill B16-F10 tumour cell target preparations differing in their expression of B7-1 and IFN-gamma/-beta treatment. When control B16-F10 (B7-1 negative, non-IFN treated) cells were used as targets, low levels of CTL activity were detected albeit that the resulting levels of cell killing varied slightly between 0 to ˜5% of maximum lysis over eight separate experiments (an example curve is shown in FIG. 14A). IFN-gamma/-beta treated B16-F10 cells used as targets provoked a greater cell killing response (between 15-22% maximum lysis), consistently well above the levels of killing of control B16-F10 cells not treated with IFN. Quantitative comparison of the relative killing of targets based on the method outlined in (41) could not be made because of the low level of killing of the control B16-F10 cells. Results from repeated experiments comparing the effect of B7-1 expression on the B16-F10 target cells treated with or without IFN-gamma/-beta are presented in FIG. 14A. Thus, IFN-gamma/-beta treated B16-F10/B7-1^(hi) cell targets were compared with non-treated B16-F10/B7-1^(hi) cell targets. The results revealed plateaus of cell lysis of between 60-70% for the IFN-gamma/-beta treated B₇-1^(hi) cells. These values were much higher compared to the range of values (between 15-40%) obtained in several different experiments using non-treated B16-F10/B7-1^(hi) cells as targets. Quantitative analysis of the relative lytic units from the results in FIG. 14A revealed that the combination of high B7-1 expression and IFN-gamma/-beta treatment of B16-F10 cells increased their cytolysis by nearly sixfold (FIG. 14B) over the killing of B16-F10 cells treated with IFN-gamma/-beta. In addition, the latter cells were killed almost fivefold more efficiently than B16-F10B7-1^(hi) target cells not treated with the IFNs. Thus, the IFN treatment resulted in an overall ˜27 fold increase of killing of B7-1 positive B16-F10 cells.

On the basis of these results, it can be concluded that B7-1 negative B16-F10 cells not treated with IFN were killed at low efficiency by cytotoxic immune effector cells resulting from the use of an immunogenic vaccine comprising IFN-gamma/-beta treated B16-F10/B7-1^(hi) cells. In addition, expression of B7-1 together with the effects of IFN-gamma/-beta treatment on the target tumour cells greatly enhances the ability of CTLs to bind and kill these tumour cells.

Example 22

CD8⁺ T Cells Produced are Specific for B16-F10 and Not Syngeneic EL-4 Thymoma Cells.

When syngeneic EL-4 thymoma cells were tested and compared with B16-F10 melanoma cells as targets, the results in two separate experiments showed a low level of cytolysis of EL-4 target cells, more noticeably at the higher E:T ratios >6:1 (see FIG. 15). However, based on lyric unit analysis (results not shown) the susceptibility of EL-4 target cells to cytolysis was quantitatively estimated to be tenfold lower than the killing of the B16-F10/B7-1hi cells. Thus, the CTL reactivity towards the syngeneic EL-4 thymoma cells was considerably lower.

Discussion of the Examples

The immunopotentiating composition has been designed and established to enhance the production of cytolytic anti-tumour cell activity in animals. When the appropriate combination of modifications is applied, significant gains in killer cell activity by as much as 5-20 times can be produced. The techniques involve the use of recombinant interferons that are readily available now from commercial sources. The procedure was designed on the basis of theoretical principles derived from observations that the properties of the interferons include many aspects related to increasing the antigen processing and presentation of cells. Focusing on three of the most important surface components, ICAM-1, B7-1 and MHC Class I, the effect of gamma priming, and Stat1 upregulation enabled us to formulate the subject immunopotentiating composition. Firstly, fluorescence analysis of cells treated with either type I or type II interferons alone or in combination allowed us to determine the optimal treatments inducing the highest simultaneous expression of MHC Class I, B7-1 and ICAM-1 receptors required for efficient CTL responses. Thus, interferon gamma for 72 h and interferon beta for 48 h, including a 24 h priming incubation with interferon gamma produced values of MHC class I and ICAM-1 expression close to the maxima plateau level. Surface expression levels then declined over longer time periods of incubation.

In the case of the B16 murine melanoma cell line, however, despite the large increase in surface expression of MHC Class I and ICAM-1 molecules, no B7-1 was detected. This is likely to be a common problem given that many cancers are B7 negative (for example, see (40)). For this reason, the inventors adopted the practice of transfecting cancer cells to express the B7-1 antigen. The important role played by B7-1 and its action as a co-stimulatory molecule signalling through the CTL CD28 receptor has been previously well established in other studies both in vitro and in vivo in promoting CTL survival and expansion as opposed to T cell anergy in the absence of B7-1 (34, 35). Interestingly, despite the absence of detectable B7-1 on the surface of the interferon treated wild type B16-F10 cells, these cells proved to be much better targets than the untreated wild type B16-F10 cells (FIGS. 6-9). This result held not only for the syngeneic, but also for allogeneic MLC (FIGS. 11, 12). Thus, the combination of interferon treatment and B7-1 are important for the induction of sufficient immune responses to allow efficient killing of the target cancer cells.

The modifications involved in producing B7-1 expressing B16-F10 cells by transfection with selectable expression vectors did not affect the ability of the interferon treatments to induce comparable increases in the levels of ICAM-1 and MHC Class I expression on the selectable B7-1 positive clones (FIG. 5). This was important as it then allowed us to compare interferon treated B7-1 positive with the B7-1 negative wild type B16-F10 cell lines for the propensity to act as efficient stimulators and/or target cells. The effect of B7-1 expression was very significant and cells treated with interferons, when used as immunogen, MLC stimulators and as targets yielded efficiencies of cytolytic responses similar to those obtained with allogeneic MLC on interferon treated B 16 cell preparations.

The results of the cytotoxicity assays showing the importance of the combined interferon treatment and B7 expression in the immunopotentiating composition should be considered together with the outcomes of the preclinical trial. Although the B7Hi vaccine alone did protect 70-75% of the animals, it was not as good as the outcome of 90% with the interferon combined (FIG. 13). The cytotoxicity assays showed a considerable improvement with a gain of 5 times greater activity using the interferon combination compared to without interferon. On balance, it can be concluded that the best formulation comprises combined interferon treatment and B7 expression in order to maximise antigen presenting function of the tumour cells thereby providing an optimal immunopotentiating vaccine that promotes high levels of anti-tumour CTL activity and protection of vaccinated mice from challenge with tumour cells.

The disclosure of every patent, patent application, and publication cited herein is hereby incorporated herein by reference in its entirety.

The citation of any reference herein should not be construed as an admission that such reference is available as “Prior Art” to the instant application

Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. Those of skill in the art will therefore appreciate that, in light of the instant disclosure, various modifications and changes can be made in the particular embodiments exemplified without departing from the scope of the present invention. All such modifications and changes are intended to be included within the scope of the appended claims.

Tables

TABLE 1 Induction of MHC Class I antigen expression on B16-F10 by IFNs Mean Factor Time course of fluorescence Mean % increase over IFN treatment (ungated fluorescence popln control (h) values)* (gated values)** gated (ungated) No IFN Control 11 ± 1  1 IFNγ (24) 617 ± 5  642 97 55 IFNγ (48) 915 ± 0  940 99 81 IFNγ (72) 758 ± 3  833 92 67 IFNγ (96) 905 ± 5  1057 87 80 IFNβ (24) 269 ± 5  293 97 24 IFNβ (48) 202 ± 2  220 99 18 IFNβ (72) 330 ± 4  365 94 29 IFNβ (96) 29 ± 2  73 44 3 IFNγ(48)β(24) 862 ± 4  993 88 76 IFNγ(72)β(48) 1336 ± 10  1381 98 118 IFNγ(96)β(72) 635 ± 4  683 95 56 IFNγ(120)β(96) 935 ± 5  1060 89 83 *Mean ± standard error from three experiments. **Gated values were obtained by subtracting the immunofluorescence peak profile of control untreated cells from the profile of cells treated with IFN as indicated.

TABLE 2A Induction of B7-1 antigen expression on B16-F10 by IFNs Interferon Mean Factor treatment time fluorescence Mean increase over course (ungated fluorescence % popln control (hours) values) (gated values)* gated (ungated) No IFN Control 8 1 IFNγ (24) 36 77 47 5 IFNγ (48) 30 75 40 4 IFNγ (72) 6 80 6 1 IFNγ (96) 13 40 27 2 IFNβ (24) 30 102 28 4 IFNβ (48) 12 79 14 2 IFNβ (72) 5 58 6 1 IFNβ (96) 8 63 11 1 IFNγ(48)β(24) 35 76 44 4 IFNγ(72)β(48) 22 63 32 3 IFNγ(96)β(72) 6 73 6 1 IFNγ(120)β(96) 20 54 34 3 *Gated values were obtained by subtracting the immunofluorescence peak profile of control untreated cells from the profile of cells treated with IFN as indicated.

TABLE 2B Induction of ICAM-1 antigen expression on B16-F10 by IFNs Mean Factor fluorescence Mean % increase over Time course of (ungated fluorescence popln control IFN treatment (h) values)* (gated values)** gated (ungated) No IFN Control 6 ± 2 1 IFNγ (24) 34 ± 14 64 ± 13 60 6 IFNγ (48) 19 ± 7  51 ± 8  42 3 IFNγ (72) 14 ± 6  49 ± 10 29 2 IFNγ (96) 19 ± 9  49 ± 9  44 3 IFNβ (24) 16 ± 7  45 ± 7  40 3 IFNβ (48) 15 ± 8  56 ± 11 31 3 IFNβ (72) 10 ± 6  65 ± 15 18 2 IFNβ (96) 11 ± 4  47 ± 5  27 2 IFNγ(48)β(24) 30 ± 8  56 ± 10 42 5 IFNγ(72)β(48) 28 ± 13 63 ± 15 49 5 IFNγ(96)β(72) 21 ± 10 54 ± 14 42 4 *Mean ± standard error from three experiments. **Gated values were obtained by subtracting the immunofluorescence peak profile of control untreated cells from the profile of cells treated with IFN as indicated.

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What is claimed is:
 1. A composition comprising: a population of animal cancer cells that express a T cell co-stimulatory B-7 molecule selected from the group consisting of B7-1 and B7-2 on the surface of said cells at a level at least 10-fold above a wild-type population of said cells, said cells having been treated with a type II interferon (IFN) such that said cells have enhanced antigen presenting function relative to animal cancer cells that have not been treated with a type II interferon (IFN); and a type I IFN in isolated form.
 2. The composition of claim 1, wherein the cells are cultured in the presence of a type II IFN from about 16 to about 96 hours and subsequently in the presence of at least one type I IFN from about 16 to about 72 hours.
 3. The composition of claim 1, wherein the type II IFN is present in the culture medium at a concentration of about 100 to about 2000 international units/mL.
 4. The composition of claim 1, wherein the type I IFN is present in the culture medium at a concentration of about 100 to about 2000 international units/mL.
 5. The composition of claim 1, wherein the animal cancer cells have been cultured in the presence of a type II interferon (IFN) in isolated form and both of a first type I IFN in isolated form and a second type I IFN in isolated form for a time and under conditions sufficient to enhance the antigen presenting function of said cells.
 6. The composition of any one of claims 1 to 5, wherein an individual type I IFN is selected from the group consisting of an IFN-alpha and an IFN-beta.
 7. The composition of claim 1, wherein the T cell co-stimulatory molecule is a B7-1 molecule.
 8. The composition of claim 7, wherein the B7-1 molecule comprises the sequence set forth in SEQ ID NO:
 14. 9. The composition of claim 1, wherein the T cell co-stimulatory molecule is a B7-2 molecule.
 10. The composition of claim 9, wherein the B7-2 molecule comprises the sequence set forth in SEQ ID NO:
 16. 11. The composition of claim 1, wherein the T cell co-stimulatory B7 molecule is a membrane molecule of the cells, wherein at least a portion of said molecule is exposed to the extracellular environment.
 12. The composition of claim 1, wherein the B7- 1 molecule comprises the sequence set forth in SEQ ID NO: 18 or
 20. 13. The composition of claim 1, wherein the cancer cells are derived from a tissue, organ or system selected from the group consisting of lung, breast, uterus, cervix, ovaries, colon, pancreas, prostate, testes, stomach, bladder, kidney, bone, liver, the reticuloendothelial system, esophagus, brain, skin, and soft tissue.
 14. The composition of claim 1, wherein the cancer cells are selected from the group consisting of melanoma cells and mammary carcinoma cells.
 15. The composition of claim 1, wherein said cells have been inactivated.
 16. A composition, wherein said composition elicits an immune response against a target antigen, and wherein said composition comprises the composition of claim 1 and, wherein said cells have been washed to remove said IFNs and wherein an antigen corresponding to said target antigen has been loaded onto IFN-treated animal cells.
 17. The composition of claim 1, wherein said population of animal cancer cells has been isolated from a heterogeneous population of animal cells.
 18. The composition of claim 1, wherein said population of animal cancer cells has been modified to express the T cell co-stimulatory B7 molecule by introduction into the cells of a polynucleotide from which the T cell co-stimulatory B7 molecule is expressible.
 19. The composition of claim 1, wherein the T cell co-stimulatory B-7 molecule is B7-
 1. 